Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Computed at the statutory rate	$ 63,442	$ 55,875	$ 54,223
State income taxes, net of federal tax benefit	5,860	5,015	1,582
Discrete items related to ASU 2016-09	(38)	(2,439)	(1,480)
Tax exempt interest income	(4,390)	(3,168)	(4,209)
Tax exempt earnings on BOLI	(852)	(869)	(926)
Federal tax credits	(2,933)	(3,003)	(1,586)
Impact of DTA remeasurement	0	0	11,471
Other differences, net	3,176	(1,053)	2,908
Provision for income taxes	$ 64,265	$ 50,358	$ 61,983