XML 69 R56.htm IDEA: XBRL DOCUMENT v3.22.0.1
Available for Sale Securities (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Available for Sale Securities [Line Items]      
Available for sale securities, Amortized Cost $ 13,064,436 $ 12,609,850  
Available for sale securities 13,157,817 13,050,665  
Available for sale securities, Gross Unrealized Gain 207,361 449,654  
Available for sale securities, Gross Unrealized Loss (113,980) (8,839)  
Available for Sale Securities, Realized Gain (Loss) [Abstract]      
Proceeds from sales of available for sale securities 622,881 384,507 $ 1,211,718
Available for sale securities, Gross realized gains 5,702 9,976 14,996
Available for sale securities, Gross realized losses (1,998) (66) (9,399)
Available for sale securities, Related federal and state income tax expense 889 2,524 $ 1,425
Available for sale securities, Pledged as Collateral, Fair Value 10,200,000 11,600,000  
Fixed maturity securities [Member]      
Available for Sale Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]      
Available for sale securities, Debt Maturities, Less than One Year, Amortized Cost 74,454    
Available for sale securities, Debt Maturities, One to Five Years, Amortized Cost 1,881,944    
Available for sale securities, Debt Maturities, Six to Ten Years, Amortized Cost 2,695,022    
Available for sale securities, Debt Maturities, Over Ten Years, Amortized Cost 493,804    
Available for sale securities, Maturity, Allocated and Single Maturity Date, Amortized Cost 5,145,224    
Available for Sale Securities, Maturity, Fair Value, Rolling Maturity [Abstract]      
Available for sale securities, Debt Maturities, Less Than One Year, Fair Value 74,874    
Available for sale securities, Debt Maturities, One to Five Years, Fair Value 1,898,237    
Available for sale securities, Debt Maturities, Six to Ten Years, Fair Value 2,657,759    
Available for sale securities, Debt Maturities, Over Ten Years, Fair Value 495,992    
Available for sale securities, Debt Maturities, Single Maturity Date, Fair value $ 5,126,862    
Available for sale securities, Debt Maturities, Weighted Average Maturity [1] 6.76    
U.S. Treasury [Member]      
Available for Sale Securities [Line Items]      
Available for sale securities, Amortized Cost $ 1,001 500  
Available for sale securities 1,000 508  
Available for sale securities, Gross Unrealized Gain 0 8  
Available for sale securities, Gross Unrealized Loss (1) 0  
Municipal securities [Member]      
Available for Sale Securities [Line Items]      
Available for sale securities, Amortized Cost 515,551 165,318  
Available for sale securities 508,365 167,979  
Available for sale securities, Gross Unrealized Gain 1,302 2,666  
Available for sale securities, Gross Unrealized Loss (8,488) (5)  
Commercial agency mortgage-backed securities [Member]      
Available for Sale Securities [Line Items]      
Available for sale securities, Amortized Cost 4,628,172 3,406,956  
Available for sale securities 4,617,025 3,508,465  
Available for sale securities, Gross Unrealized Gain 36,868 103,590  
Available for sale securities, Gross Unrealized Loss (48,015) (2,081)  
Other debt securities [Member]      
Available for Sale Securities [Line Items]      
Available for sale securities, Amortized Cost 500 500  
Available for sale securities 472 472  
Available for sale securities, Gross Unrealized Gain 0 0  
Available for sale securities, Gross Unrealized Loss (28) (28)  
Residential Mortgage Backed Securities [Member]      
Available for Sale Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]      
Available for sale securities, Maturity, without Single Maturity Date, Amortized Cost [2] 7,919,212    
Available for Sale Securities, Maturity, Fair Value, Rolling Maturity [Abstract]      
Available for sale securities, Debt Maturities, without Single Maturity Date, Fair value $ 8,030,955    
Available for sale securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities 3 years 8 months 12 days    
Residential agency mortgage-backed securities [Member]      
Available for Sale Securities [Line Items]      
Available for sale securities, Amortized Cost $ 7,908,587 9,019,013  
Available for sale securities 8,006,616 9,340,471  
Available for sale securities, Gross Unrealized Gain 155,477 328,183  
Available for sale securities, Gross Unrealized Loss (57,448) (6,725)  
Residential non-agency mortgage-backed securities [Member]      
Available for Sale Securities [Line Items]      
Available for sale securities, Amortized Cost 10,625 17,563  
Available for sale securities 24,339 32,770  
Available for sale securities, Gross Unrealized Gain 13,714 15,207  
Available for sale securities, Gross Unrealized Loss $ 0 $ 0  
[1] Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.
[2] The average expected lives of residential mortgage-backed securities were 3.7 years based upon current prepayment assumptions.