Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2010
OPERATIONS:
Net interest income (loss)	$ 118,787	$ 121,824
Provision for loan losses	14,061	22,349
Other income	51,726	52,756
Other expenses	113,768	114,445
Net income (loss)	30,344	27,560	27,560
AVERAGES :
Assets	14,496,937	14,270,871
Commercial [Member]
OPERATIONS:
Net interest income (loss)	63,853	67,575
Provision for loan losses	9,104	10,017
Other income	14,309	14,793
Other expenses	43,351	37,613
Net income (loss)	16,709	22,579
AVERAGES :
Assets	6,328,473	6,094,547
Retail [Member]
OPERATIONS:
Net interest income (loss)	54,277	55,771
Provision for loan losses	2,537	5,949
Other income	25,265	24,191
Other expenses	57,481	60,830
Net income (loss)	12,691	8,569
AVERAGES :
Assets	2,910,354	2,954,002
Wealth [Member]
OPERATIONS:
Net interest income (loss)	4,598	4,823
Provision for loan losses	225	619
Other income	8,068	8,193
Other expenses	10,214	10,297
Net income (loss)	1,447	1,365
AVERAGES :
Assets	236,571	243,249
Other [Member]
OPERATIONS:
Net interest income (loss)	(3,941)	(6,345)
Provision for loan losses	2,195	5,764
Other income	4,084	5,579
Other expenses	2,722	5,705
Net income (loss)	(503)	(4,953)
AVERAGES :
Assets	$ 5,021,539	$ 4,979,073