Loans Part 2 (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	$ 10,561,213,000		$ 10,561,213,000		$ 10,440,533,000
Individually measured for impairment, recorded investment	176,331,000		176,331,000		202,503,000
Total	10,737,544,000	10,882,717,000	10,737,544,000	10,882,717,000	10,643,036,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	252,803,000		252,803,000		259,103,000
Individually measured for impairment, related allowance	6,683,000		6,683,000		7,132,000
Total measured for impairment, related allowance	286,611,000	299,489,000	286,611,000	299,489,000
Activity in allowance for credit losses [Abstract]
Beginning balance	289,549,000		292,971,000
Provision for loan losses	5,580,000		12,476,000
Loans charged off	(12,774,000)		(28,006,000)
Recoveries	4,256,000		9,170,000
Ending balance	286,611,000	299,489,000	286,611,000	299,489,000
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	13,625,000		14,271,000
Provision for off-balance sheet credit losses	(2,880,000)		(3,526,000)
Ending balance	10,745,000		10,745,000
Total provision for credit losses - Ending balance	2,700,000	36,040,000	8,950,000	78,140,000
Commercial Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	6,125,434,000		6,125,434,000		5,895,674,000
Individually measured for impairment, recorded investment	53,162,000		53,162,000		38,322,000
Total	6,178,596,000		6,178,596,000		5,933,996,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	111,131,000		111,131,000		102,565,000
Individually measured for impairment, related allowance	2,440,000		2,440,000		2,066,000
Total measured for impairment, related allowance	113,571,000		113,571,000
Activity in allowance for credit losses [Abstract]
Beginning balance	113,706,000		104,631,000
Provision for loan losses	980,000		10,836,000
Loans charged off	(3,302,000)		(5,654,000)
Recoveries	2,187,000		3,758,000
Ending balance	113,571,000		113,571,000
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	12,256,000		13,456,000
Provision for off-balance sheet credit losses	(3,020,000)		(4,220,000)
Ending balance	9,236,000		9,236,000
Total provision for credit losses - Ending balance	(2,040,000)		6,616,000
Commercial Real Estate Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	2,073,352,000		2,073,352,000		2,126,984,000
Individually measured for impairment, recorded investment	110,363,000		110,363,000		150,366,000
Total	2,183,715,000		2,183,715,000		2,277,350,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	88,611,000		88,611,000		94,502,000
Individually measured for impairment, related allowance	3,139,000		3,139,000		4,207,000
Total measured for impairment, related allowance	91,750,000		91,750,000
Activity in allowance for credit losses [Abstract]
Beginning balance	94,535,000		98,709,000
Provision for loan losses	289,000		2,665,000
Loans charged off	(3,380,000)		(10,273,000)
Recoveries	306,000		649,000
Ending balance	91,750,000		91,750,000
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	875,000		443,000
Provision for off-balance sheet credit losses	145,000		577,000
Ending balance	1,020,000		1,020,000
Total provision for credit losses - Ending balance	434,000		3,242,000
Residential Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	1,857,112,000		1,857,112,000		1,816,184,000
Individually measured for impairment, recorded investment	10,885,000		10,885,000		12,064,000
Total	1,867,997,000		1,867,997,000		1,828,248,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	44,254,000		44,254,000		49,500,000
Individually measured for impairment, related allowance	989,000		989,000		781,000
Total measured for impairment, related allowance	45,243,000		45,243,000
Activity in allowance for credit losses [Abstract]
Beginning balance	45,649,000		50,281,000
Provision for loan losses	2,721,000		(45,000)
Loans charged off	(3,381)		(6,329,000)
Recoveries	254,000		1,336,000
Ending balance	45,243,000		45,243,000
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	155,000		131,000
Provision for off-balance sheet credit losses	25,000		49,000
Ending balance	180,000		180,000
Total provision for credit losses - Ending balance	2,746,000		4,000
Consumer Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	505,315,000		505,315,000		601,691,000
Individually measured for impairment, recorded investment	1,921,000		1,921,000		1,751,000
Total	507,236,000		507,236,000		603,442,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	8,807,000		8,807,000		12,536,000
Individually measured for impairment, related allowance	115,000		115,000		78,000
Total measured for impairment, related allowance	8,922,000		8,922,000
Activity in allowance for credit losses [Abstract]
Beginning balance	10,410,000		12,614,000
Provision for loan losses	(286,000)		(1,369,000)
Loans charged off	(2,711,000)		(5,750,000)
Recoveries	1,509,000		3,427,000
Ending balance	8,922,000		8,922,000
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	339,000		241,000
Provision for off-balance sheet credit losses	(30,000)		68,000
Ending balance	309,000		309,000
Total provision for credit losses - Ending balance	(316,000)		(1,301,000)
Segment Allocations [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	10,561,213,000		10,561,213,000		10,440,533,000
Individually measured for impairment, recorded investment	176,331,000		176,331,000		202,503,000
Total	10,737,544,000		10,737,544,000		10,643,036,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	252,803,000		252,803,000		259,103,000
Individually measured for impairment, related allowance	6,683,000		6,683,000		7,132,000
Total measured for impairment, related allowance	259,486,000		259,486,000		266,235,000
Activity in allowance for credit losses [Abstract]
Beginning balance					266,235,000
Ending balance	259,486,000		259,486,000		266,235,000
Unallocated Financing Receivables [Member]
Related allowance [Abstract]
Total measured for impairment, related allowance	27,125,000		27,125,000
Activity in allowance for credit losses [Abstract]
Beginning balance	25,249,000		26,736,000
Provision for loan losses	1,876,000		389,000
Ending balance	27,125,000		27,125,000
Allowance for off-balance sheet credit losses [Abstract]
Total provision for credit losses - Ending balance	$ 1,876,000		$ 389,000