Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Computed at the statutory rate	$ 22,071	$ 13,880	$ 49,646	$ 41,731
State income taxes, net of federal tax benefit	2,956	986	5,721	4,073
Tax exempt interest income	(1,105)	(833)	(3,090)	(2,292)
Tax exempt earnings on BOLI	(225)	(186)	(619)	(562)
Federal tax credits	(730)	0	(2,188)	0
Other differences, net	308	(2,945)	1,819	(4,299)
Provision for income taxes	$ 23,275	$ 10,902	$ 51,289	$ 38,651