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, 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]
Income tax expense using the statutory Federal income tax rate of 21% in 2019 and 2018, and 35% in 2017, on income before taxes									$ 100,821	$ 96,628	$ 136,499
Increase (decrease) in tax resulting from:
Tax-exempt interest, net of interest expense disallowance									(3,958)	(3,869)	(4,658)
State taxes, net of federal tax benefit									24,600	23,584	15,115
Income earned on bank owned life insurance									(959)	(1,002)	(1,167)
Excess tax benefits on share based compensation									(1,447)	(3,107)	(5,470)
Re-measurement of net deferred tax liabilities									0	(1,209)	(10,402)
Transition tax on deferred foreign earnings									0	0	2,850
Meals, entertainment and related expenses									2,148	1,840	1,710
FDIC insurance expense									1,274	1,832	0
Non-deductible compensation expense									1,019	1,366	55
Foreign subsidiary, net									1,979	1,591	(271)
Tax benefits related to tax credit investments, net									(513)	(656)	(698)
Other, net									(560)	(31)	(1,248)
Total income tax expense	$ 30,718	$ 35,480	$ 28,707	$ 29,499	$ 28,005	$ 30,866	$ 32,011	$ 26,085	$ 124,404	$ 116,967	$ 132,315