XML 108 R95.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Taxes - Reconciliation From Statutory Rate to Effective Tax (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Disclosure [Abstract]                      
Tax expense at statutory rate of 35%                 $ 49,167 $ 43,674 $ 42,057
Increase (decrease) in taxes resulting from:                      
State tax, net of federal income tax benefit                 2,185 1,215 2,072
Tax-exempt interest income                 (5,097) (5,286) (5,520)
Bank-owned life insurance                 (2,343) (1,915) (1,871)
Enactment of Tax Act                 3,912 0 0
Other, net                 (1,296) (708) (297)
Income tax expense (benefit) $ 15,740 $ 11,969 $ 10,451 $ 8,368 $ 10,182 $ 9,281 $ 8,781 $ 8,736 $ 46,528 $ 36,980 $ 36,441