Loans and Allowances for Credit Losses Part 2 (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Allowance for loan losses [Roll Forward]
Beginning balance	$ 185,396,000	$ 215,507,000
Provision for loan losses	410,000	(7,190,000)
Loans charged off	(2,848,000)	(8,909,000)
Recoveries	5,360,000	6,557,000
Ending balance	188,318,000	205,965,000
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	2,088,000	1,915,000
Provision for off-balance sheet credit losses	(410,000)	(810,000)
Ending balance	1,678,000	1,105,000
Total provision for credit losses	0	(8,000,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	12,973,148,000	11,961,144,000	12,691,892,000
Individually measured for impairment, recorded investment	104,706,000	132,420,000	100,372,000
Total	13,077,854,000	12,093,564,000	12,792,264,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	157,194,000	162,126,000	156,229,000
Individually measured for impairment, related allowance	4,159,000	1,027,000	954,000
Total measured for impairment, related allowance	188,318,000	205,965,000
Commercial [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	79,180,000	65,280,000
Provision for loan losses	4,225,000	(1,956,000)
Loans charged off	(144,000)	(298,000)
Recoveries	1,985,000	3,393,000
Ending balance	85,246,000	66,419,000
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	119,000	475,000
Provision for off-balance sheet credit losses	457,000	(70,000)
Ending balance	576,000	405,000
Total provision for credit losses	4,682,000	(2,026,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	8,032,659,000	7,398,444,000	7,926,461,000
Individually measured for impairment, recorded investment	19,047,000	19,861,000	16,760,000
Total	8,051,706,000	7,418,305,000	7,943,221,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	81,813,000	66,071,000	78,607,000
Individually measured for impairment, related allowance	3,433,000	348,000	573,000
Total measured for impairment, related allowance	85,246,000	66,419,000
Commercial Real Estate [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	41,573,000	54,884,000
Provision for loan losses	(1,591,000)	(2,680,000)
Loans charged off	(220,000)	(4,800,000)
Recoveries	1,827,000	1,124,000
Ending balance	41,589,000	48,528,000
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	1,876,000	1,353,000
Provision for off-balance sheet credit losses	(836,000)	(735,000)
Ending balance	1,040,000	618,000
Total provision for credit losses	(2,427,000)	(3,415,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	2,592,102,000	2,219,985,000	2,374,503,000
Individually measured for impairment, recorded investment	39,305,000	65,175,000	40,850,000
Total	2,631,407,000	2,285,160,000	2,415,353,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	41,404,000	48,270,000	41,440,000
Individually measured for impairment, related allowance	185,000	258,000	133,000
Total measured for impairment, related allowance	41,589,000	48,528,000
Residential Mortgage [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	29,465,000	41,703,000
Provision for loan losses	(516,000)	(274,000)
Loans charged off	(996,000)	(1,779,000)
Recoveries	354,000	572,000
Ending balance	28,307,000	40,222,000
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	90,000	78,000
Provision for off-balance sheet credit losses	(28,000)	(6,000)
Ending balance	62,000	72,000
Total provision for credit losses	(544,000)	(280,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	1,973,295,000	1,967,238,000	2,010,483,000
Individually measured for impairment, recorded investment	45,380,000	45,212,000	41,543,000
Total	2,018,675,000	2,012,450,000	2,052,026,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	27,766,000	39,923,000	29,217,000
Individually measured for impairment, related allowance	541,000	299,000	248,000
Total measured for impairment, related allowance	28,307,000	40,222,000
Consumer [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	6,965,000	9,453,000
Provision for loan losses	(460,000)	(905,000)
Loans charged off	(1,488,000)	(2,032,000)
Recoveries	1,194,000	1,468,000
Ending balance	6,211,000	7,984,000
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	3,000	9,000
Provision for off-balance sheet credit losses	(3,000)	1,000
Ending balance	0	10,000
Total provision for credit losses	(463,000)	(904,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	375,092,000	375,477,000	380,445,000
Individually measured for impairment, recorded investment	974,000	2,172,000	1,219,000
Total	376,066,000	377,649,000	381,664,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	6,211,000	7,862,000	6,965,000
Individually measured for impairment, related allowance	0	122,000	0
Total measured for impairment, related allowance	6,211,000	7,984,000
Specific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance			157,183,000
Ending balance	161,353,000	163,153,000	157,183,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	12,973,148,000	11,961,144,000	12,691,892,000
Individually measured for impairment, recorded investment	104,706,000	132,420,000	100,372,000
Total	13,077,854,000	12,093,564,000	12,792,264,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance	157,194,000	162,126,000	156,229,000
Individually measured for impairment, related allowance	4,159,000	1,027,000	954,000
Total measured for impairment, related allowance	161,353,000	163,153,000	157,183,000
Nonspecific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	28,213,000	44,187,000
Provision for loan losses	(1,248,000)	(1,375,000)
Loans charged off	0	0
Recoveries	0	0
Ending balance	26,965,000	42,812,000
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	0	0
Provision for off-balance sheet credit losses	0	0
Ending balance	0	0
Total provision for credit losses	(1,248,000)	(1,375,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	0	0	0
Individually measured for impairment, recorded investment	0	0	0
Total	0	0	0
Related allowance [Abstract]
Collectively measured for impairment, related allowance	0	0	0
Individually measured for impairment, related allowance	0	0	0
Total measured for impairment, related allowance	$ 26,965,000	$ 42,812,000