Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
OPERATIONS:
Net interest income	$ 185,156	$ 185,623
Provision/ (recapture) for loan losses	7,809	8,248
Noninterest Income	67,394	65,847
Other expenses	166,963	160,652
Net income	54,136	57,139
AVERAGES :
Assets	25,770,857	24,905,094
Loans	16,079,447	15,427,181
Earning assets	22,890,082	22,100,417
Deposits	20,635,665	19,788,925
Economic capital	2,970,167	2,866,362
Operating Segments | Commercial Loan
OPERATIONS:
Net interest income	102,619	99,844
Provision/ (recapture) for loan losses	5,772	(526)
Noninterest Income	21,179	22,490
Other expenses	61,020	61,653
Net income	37,054	39,785
AVERAGES :
Assets	9,592,202	9,454,218
Loans	9,709,788	9,506,529
Earning assets	10,074,234	9,794,483
Deposits	7,478,489	6,886,945
Economic capital	1,252,294	848,890
Operating Segments | Retail
OPERATIONS:
Net interest income	94,728	91,095
Provision/ (recapture) for loan losses	4,047	7,533
Noninterest Income	23,594	21,737
Other expenses	88,694	88,271
Net income	16,628	11,068
AVERAGES :
Assets	6,232,255	5,845,417
Loans	6,020,757	5,570,590
Earning assets	6,027,689	5,582,849
Deposits	11,025,256	11,124,158
Economic capital	872,762	479,188
Operating Segments | Wealth
OPERATIONS:
Net interest income	6,552	5,353
Provision/ (recapture) for loan losses	(155)	(170)
Noninterest Income	14,309	13,976
Other expenses	13,353	13,719
Net income	4,981	3,756
AVERAGES :
Assets	305,566	302,186
Loans	297,143	292,016
Earning assets	297,143	292,016
Deposits	1,319,711	1,240,960
Economic capital	131,588	55,187
Other
OPERATIONS:
Net interest income	(18,743)	(10,669)
Provision/ (recapture) for loan losses	(1,855)	1,411
Noninterest Income	8,312	7,644
Other expenses	3,896	(2,991)
Net income	(4,527)	2,530
AVERAGES :
Assets	9,640,834	9,303,273
Loans	51,759	58,046
Earning assets	6,491,016	6,431,069
Deposits	812,209	536,862
Economic capital	$ 713,523	$ 1,483,097