XML 59 R48.htm IDEA: XBRL DOCUMENT v3.19.1
Securities - Securities, with Unrealized Losses Segregated by Length of Impairment (Detail) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Schedule of Available-for-Sale Securities [Line Items]    
Held to Maturity, Less than 12 Months, Estimated Fair Value $ 0  
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 0  
Held to Maturity, More than 12 Months, Estimated Fair Value 4,400  
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 55  
Held to Maturity, Total Estimated Fair Value 4,400  
Held-to-maturity Securities, Gross Unrealized Losses 55 $ 637
Available for Sale, Less than 12 Months, Estimated Fair Value 60,600  
Available for Sale, Less than 12 Months, Unrealized Losses 1,334  
Available for Sale, More than 12 Months, Estimated Fair Value 4,077,229  
Available for Sale, More than 12 Months, Unrealized Losses 30,740  
Available for Sale, Total Estimated Fair Value 4,137,829  
Available-for-sale Securities, Gross Unrealized Loss, before Tax 32,074 108,737
Residential mortgage-backed securities [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Held to Maturity, Less than 12 Months, Estimated Fair Value 0  
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 0  
Held to Maturity, More than 12 Months, Estimated Fair Value 2,039  
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 53  
Held to Maturity, Total Estimated Fair Value 2,039  
Held-to-maturity Securities, Gross Unrealized Losses 53 85
Available for Sale, Less than 12 Months, Estimated Fair Value 1,716  
Available for Sale, Less than 12 Months, Unrealized Losses 1  
Available for Sale, More than 12 Months, Estimated Fair Value 183,952  
Available for Sale, More than 12 Months, Unrealized Losses 3,353  
Available for Sale, Total Estimated Fair Value 185,668  
Available-for-sale Securities, Gross Unrealized Loss, before Tax 3,354 6,547
States and political subdivisions [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Held to Maturity, Less than 12 Months, Estimated Fair Value 0  
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 0  
Held to Maturity, More than 12 Months, Estimated Fair Value 2,361  
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 2  
Held to Maturity, Total Estimated Fair Value 2,361  
Held-to-maturity Securities, Gross Unrealized Losses 2 552
Available for Sale, Less than 12 Months, Estimated Fair Value 58,884  
Available for Sale, Less than 12 Months, Unrealized Losses 1,333  
Available for Sale, More than 12 Months, Estimated Fair Value 739,744  
Available for Sale, More than 12 Months, Unrealized Losses 11,216  
Available for Sale, Total Estimated Fair Value 798,628  
Available-for-sale Securities, Gross Unrealized Loss, before Tax 12,549 72,690
Other Investments [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Held-to-maturity Securities, Gross Unrealized Losses 0 0
Available-for-sale Securities, Gross Unrealized Loss, before Tax 0 0
US Treasury Securities [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Available for Sale, Less than 12 Months, Estimated Fair Value 0  
Available for Sale, Less than 12 Months, Unrealized Losses 0  
Available for Sale, More than 12 Months, Estimated Fair Value 3,153,533  
Available for Sale, More than 12 Months, Unrealized Losses 16,171  
Available for Sale, Total Estimated Fair Value 3,153,533  
Available-for-sale Securities, Gross Unrealized Loss, before Tax $ 16,171 $ 29,500