Quarterly report pursuant to Section 13 or 15(d)

Fair Value, Measurement Inputs, Disclosure (Details)

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Fair Value, Measurement Inputs, Disclosure (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Debt Securities, Available-for-sale, Categorized as Level 2 Assets 99.20478%          
Debt Securities, Available-for-sale, Categorized as Level 3 Assets 0.80%          
Assets Reported at Fair Value, Debt Securities, Available-for-sale 91.60%          
Mortgage Servicing Rights Categorized as Level 3 Assets 100.00%          
Mortgage Loans Held-for-sale Categorized as Level 2 Assets 1.60%          
Mortgage Loans Held-for-sale Categorized as Level 3 Assets 98.40%          
Interest Rate Swaps, Swaptions and Credit Default Swaps Categorized as Level 2 Assets (Liabilities) 100.00%          
Inverse Interest-only Securities Categorized as Level 2 Assets 100.00%          
Agency To-be-Announced Securities Categorized as Level 1 Assets (Liabilities) 100.00%          
Mortgage servicing rights $ 1,450,261 $ 1,301,023 $ 1,086,717 $ 898,025 $ 747,580 $ 693,815
Derivative assets, at fair value 257,917   309,918      
Equity securities 30,425   29,413      
Derivative liabilities, at fair value 39,429   31,903      
Fair Value, Measurements, Recurring [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Available-for-sale securities 19,293,354   21,220,819      
Mortgage servicing rights 1,450,261   1,086,717      
Residential mortgage loans held-for-sale 28,813   30,414      
Derivative assets, at fair value 257,917   309,918      
Equity securities 30,425   29,413      
Total assets 21,060,770   22,677,281      
Derivative liabilities, at fair value 39,429   31,903      
Total liabilities 39,429   31,903      
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Available-for-sale securities 0   0      
Mortgage servicing rights 0   0      
Residential mortgage loans held-for-sale 0   0      
Derivative assets, at fair value 12,252   913      
Equity securities 30,425   29,413      
Total assets 42,677   30,326      
Derivative liabilities, at fair value 18,190   1,930      
Total liabilities 18,190   1,930      
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Available-for-sale securities 19,139,930   21,067,678      
Mortgage servicing rights 0   0      
Residential mortgage loans held-for-sale 462   474      
Derivative assets, at fair value 245,665   309,005      
Equity securities 0   0      
Total assets 19,386,057   21,377,157      
Derivative liabilities, at fair value 21,239   29,973      
Total liabilities 21,239   29,973      
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Available-for-sale securities 153,424   153,141      
Mortgage servicing rights 1,450,261   1,086,717      
Residential mortgage loans held-for-sale 28,351   29,940      
Derivative assets, at fair value 0   0      
Equity securities 0   0      
Total assets 1,632,036   1,269,798      
Derivative liabilities, at fair value 0   0      
Total liabilities $ 0   $ 0