Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
OPERATIONS:
Net interest income	$ 193,578	$ 203,340	$ 583,057	$ 512,717
Provision for Loan, Lease, and Other Losses	9,192	6,379	38,982	23,634
Noninterest Income	69,733	71,090	209,564	197,923
Other expenses	163,145	210,599	499,878	505,633
Net income	63,898	40,715	176,872	126,510
AVERAGES :
Assets	24,583,776	24,013,594	24,337,653	20,632,658
Total commercial
OPERATIONS:
Net interest income	105,191	117,476	317,178	300,423
Provision for Loan, Lease, and Other Losses	(7,642)	(27)	(7,476)	6,866
Noninterest Income	21,096	21,364	69,083	60,980
Other expenses	58,221	57,033	181,435	151,587
Net income	49,211	53,136	137,995	131,704
AVERAGES :
Assets	9,407,684	8,685,333	9,225,407	8,020,824
Retail
OPERATIONS:
Net interest income	95,710	103,046	283,839	248,704
Provision for Loan, Lease, and Other Losses	7,627	905	25,149	7,071
Noninterest Income	28,270	30,723	80,651	88,916
Other expenses	85,954	96,153	269,331	235,518
Net income	19,759	23,910	45,506	61,985
AVERAGES :
Assets	5,700,960	5,659,553	5,565,047	4,646,817
Wealth
OPERATIONS:
Net interest income	5,119	4,286	14,596	12,727
Provision for Loan, Lease, and Other Losses	362	(736)	713	(570)
Noninterest Income	14,108	13,216	41,624	34,347
Other expenses	12,777	14,650	37,874	38,698
Net income	3,956	2,090	11,460	5,469
AVERAGES :
Assets	289,549	266,028	263,513	255,538
Nonreportable segments and reconciling items
OPERATIONS:
Net interest income	(12,442)	(21,468)	(32,556)	(49,137)
Provision for Loan, Lease, and Other Losses	8,845	6,237	20,596	10,267
Noninterest Income	6,259	5,787	18,206	13,680
Other expenses	6,193	42,763	11,238	79,830
Net income	(9,028)	(38,421)	(18,089)	(72,648)
AVERAGES :
Assets	$ 9,185,583	$ 9,402,680	$ 9,283,686	$ 7,709,479