Income Taxes (Reconciliation of the Differences Between Taxes Computed Using the Statutory Federal Income Tax Rate and Actual Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense using the statutory Federal income tax rate of 21% in 2018, and 35% in 2017 and 2016, on income before income taxes									$ 96,628	$ 136,499	$ 116,149
Increase (decrease) in tax resulting from:
Tax-exempt interest, net of interest expense disallowance									(3,869)	(4,658)	(3,634)
State taxes, net of federal tax benefit									23,584	15,115	13,017
Income earned on bank owned life insurance									(1,002)	(1,167)	(1,198)
Re-measurement of net deferred tax liabilities									(1,209)	(10,402)	0
Transition tax on deferred foreign earnings									0	2,850	0
Meals, entertainment and related expenses									1,840	1,710	1,439
FDIC insurance expense									1,832	0	0
Non-deductible compensation expense									1,366	55	77
Non-deductible compensation expense									(3,107)	(5,470)	0
Foreign subsidiary, net									1,591	(271)	(264)
Tax benefits related to tax credit investments, net									(656)	(698)	(572)
Other, net									(31)	(1,248)	(35)
Total income tax expense	$ 28,005	$ 30,866	$ 32,011	$ 26,085	$ 27,004	$ 38,622	$ 37,049	$ 29,640	$ 116,967	$ 132,315	$ 124,979