Income Taxes (Reconciliation of Effective Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory U.S federal income tax rate (as a percent)									21.00%	21.00%	35.00%
Reconciliation of income tax expense
Expected income tax expense at statutory federal tax rate									$ 24,366	$ 23,675	$ 34,039
State taxes, net of federal income tax benefit									4,837	5,184	3,641
Bank-owned life insurance									(216)	(218)	(364)
Tax-exempt interest income									(435)	(487)	(873)
Income attributable to noncontrolling interest in subsidiary									(11)	(933)	(870)
Merger and acquisition expense									0	32	138
Tax Act Adjustment									0	(707)	8,965
Investments in affordable housing projects									(369)	(358)	(653)
Other, net									97	1	(387)
Total provision for income taxes	$ 7,087	$ 7,507	$ 6,780	$ 6,895	$ 7,055	$ 6,140	$ 7,342	$ 5,652	$ 28,269	$ 26,189	$ 43,636
Effective income tax rate (as a percent)									24.40%	23.20%	44.90%