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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate reconciliation, at Federal satutory income tax rate, percent									35.00%
Income tax expense based upon the Federal statutory rate on income before income taxes									$ 116,149	$ 88,118	$ 86,251
Increase (decrease) in tax resulting from:
Tax-exempt interest, net of interest expense disallowance									(3,634)	(2,878)	(1,936)
State taxes, net of federal tax benefit									13,017	9,996	10,731
Income earned on bank owned life insurance									(1,198)	(1,562)	(896)
Meals, entertainment and related expenses									1,439	1,283	1,026
Foreign subsidiary, net									(264)	148	775
Tax benefits related to tax credit investments									(572)	(778)	(1,498)
Other, net									42	689	580
Total income tax expense	$ 33,724	$ 31,939	$ 29,930	$ 29,386	$ 20,896	$ 23,842	$ 26,295	$ 23,983	$ 124,979	$ 95,016	$ 95,033