Condensed Parent Company Financial Statements (Statements Of Income) (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
Losses on investment securities, net									$ 7,645	$ 323	$ (504)
Expenses
Interest expense	$ 24,235	$ 23,513	$ 21,794	$ 20,722	$ 20,281	$ 19,839	$ 18,349	$ 18,466	90,264	76,935	72,692
Salaries and employee benefits									405,158	382,080	335,506
(Loss) income before income taxes and equity in undistributed income of subsidiaries	88,332	85,054	79,971	78,497	56,408	62,197	70,126	63,035	331,854	251,765	246,431
Income tax benefit	(33,724)	(31,939)	(29,930)	(29,386)	(20,896)	(23,842)	(26,295)	(23,983)	(124,979)	(95,016)	(95,033)
Net income	$ 54,608	$ 53,115	$ 50,041	$ 49,111	$ 35,512	$ 38,355	$ 43,831	$ 39,052	206,875	156,749	151,398
Reportable Legal Entities | Parent Company
Income
Dividends and other revenue from subsidiaries									89,184	47,639	98,296
Losses on investment securities, net									0	0	(33)
Other income									4,344	796	221
Total income									93,528	48,435	98,484
Expenses
Interest expense									18,498	16,669	12,553
Salaries and employee benefits									34,299	38,926	30,636
Other expenses									62,778	50,425	38,428
Total expenses									115,575	106,020	81,617
(Loss) income before income taxes and equity in undistributed income of subsidiaries									(22,047)	(57,585)	16,867
Income tax benefit									31,061	30,504	22,909
Income (loss) before equity in undistributed net income of subsidiaries									9,014	(27,081)	39,776
Equity in undistributed net income of subsidiaries									197,861	183,830	111,622
Net income									$ 206,875	$ 156,749	$ 151,398