Loans and Allowances for Credit Losses Part 7 (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Financing receivable, recorded investment, aging [Abstract]
Current	$ 13,155,156,000	$ 12,509,986,000	$ 12,160,578,000
Past due 30 to 89 days	35,901,000	38,099,000	38,805,000
Past due 90 days or more	139,121,000	143,030,000	119,266,000
Nonaccrual	96,680,000	101,149,000	122,133,000
Total	13,426,858,000	12,792,264,000	12,440,782,000
Commercial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	8,347,097,000	7,922,000,000	7,681,836,000
Past due 30 to 89 days	3,436,000	4,112,000	2,974,000
Past due 90 days or more	25,000	349,000	2,441,000
Nonaccrual	17,103,000	16,760,000	20,869,000
Total	8,367,661,000	7,943,221,000	7,708,120,000
Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,416,139,000	2,347,267,000	2,382,377,000
Past due 30 to 89 days	2,005,000	2,483,000	92,000
Past due 90 days or more	25,000	150,000	0
Nonaccrual	1,619,000	1,860,000	2,277,000
Total	2,419,788,000	2,351,760,000	2,384,746,000
Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,373,081,000	2,276,036,000	2,192,771,000
Past due 30 to 89 days	315,000	1,210,000	1,769,000
Past due 90 days or more	0	42,000	2,265,000
Nonaccrual	3,669,000	4,922,000	7,448,000
Total	2,377,065,000	2,282,210,000	2,204,253,000
Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,312,255,000	1,193,905,000	1,168,686,000
Past due 30 to 89 days	11,000	338,000	0
Past due 90 days or more	0	152,000	157,000
Nonaccrual	5,885,000	6,969,000	6,700,000
Total	1,318,151,000	1,201,364,000	1,175,543,000
Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	448,656,000	391,159,000	385,257,000
Past due 30 to 89 days	703,000	0	0
Past due 90 days or more	0	0	0
Nonaccrual	3,507,000	592,000	876,000
Total	452,866,000	391,751,000	386,133,000
Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,392,718,000	1,272,660,000	1,115,187,000
Past due 30 to 89 days	16,000	0	953,000
Past due 90 days or more	0	0	0
Nonaccrual	1,422,000	1,586,000	2,670,000
Total	1,394,156,000	1,274,246,000	1,118,810,000
Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	404,248,000	440,973,000	437,558,000
Past due 30 to 89 days	386,000	81,000	160,000
Past due 90 days or more	0	5,000	19,000
Nonaccrual	1,001,000	831,000	898,000
Total	405,635,000	441,890,000	438,635,000
Commercial Real Estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,620,198,000	2,370,684,000	2,253,864,000
Past due 30 to 89 days	308,000	2,788,000	4,539,000
Past due 90 days or more	0	1,031,000	0
Nonaccrual	34,472,000	40,850,000	58,693,000
Total	2,654,978,000	2,415,353,000	2,317,096,000
Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	169,627,000	188,434,000	204,519,000
Past due 30 to 89 days	6,000	428,000	0
Past due 90 days or more	0	19,000	0
Nonaccrual	15,146,000	17,377,000	21,135,000
Total	184,779,000	206,258,000	225,654,000
Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	637,609,000	580,926,000	542,946,000
Past due 30 to 89 days	302,000	264,000	2,060,000
Past due 90 days or more	0	0	0
Nonaccrual	4,199,000	4,857,000	8,406,000
Total	642,110,000	586,047,000	553,412,000
Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	390,626,000	404,505,000	451,730,000
Past due 30 to 89 days	0	603,000	0
Past due 90 days or more	0	0	0
Nonaccrual	3,591,000	6,391,000	7,828,000
Total	394,217,000	411,499,000	459,558,000
Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	677,403,000	576,495,000	492,306,000
Past due 30 to 89 days	0	0	1,699,000
Past due 90 days or more	0	0	0
Nonaccrual	0	7,000	6,447,000
Total	677,403,000	576,502,000	500,452,000
Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	341,449,000	243,625,000	253,990,000
Past due 30 to 89 days	0	0	0
Past due 90 days or more	0	0	0
Nonaccrual	631,000	252,000	0
Total	342,080,000	243,877,000	253,990,000
Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	403,484,000	376,699,000	308,373,000
Past due 30 to 89 days	0	1,493,000	780,000
Past due 90 days or more	0	1,012,000	0
Nonaccrual	10,905,000	11,966,000	14,877,000
Total	414,389,000	391,170,000	324,030,000
Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,793,615,000	1,837,885,000	1,853,635,000
Past due 30 to 89 days	31,165,000	30,172,000	28,810,000
Past due 90 days or more	139,095,000	141,649,000	116,806,000
Nonaccrual	44,340,000	42,320,000	40,534,000
Total	2,008,215,000	2,052,026,000	2,039,785,000
Permanent mortage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	977,897,000	1,018,670,000	1,054,435,000
Past due 30 to 89 days	10,079,000	9,795,000	8,689,000
Past due 90 days or more	0	0	0
Nonaccrual	32,952,000	34,279,000	32,747,000
Total	1,020,928,000	1,062,744,000	1,095,871,000
Permanent mortgages guaranteed by US govenment agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	27,855,000	21,916,000	22,328,000
Past due 30 to 89 days	19,231,000	17,290,000	17,670,000
Past due 90 days or more	139,054,000	141,615,000	116,806,000
Nonaccrual	1,947,000	777,000	83,000
Total	188,087,000	181,598,000	156,887,000
Home equity {Member]
Financing receivable, recorded investment, aging [Abstract]
Current	787,863,000	797,299,000	776,872,000
Past due 30 to 89 days	1,855,000	3,087,000	2,451,000
Past due 90 days or more	41,000	34,000	0
Nonaccrual	9,441,000	7,264,000	7,704,000
Total	799,200,000	807,684,000	787,027,000
Consumer [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	394,246,000	379,417,000	371,243,000
Past due 30 to 89 days	992,000	1,027,000	2,482,000
Past due 90 days or more	1,000	1,000	19,000
Nonaccrual	765,000	1,219,000	2,037,000
Total	$ 396,004,000	$ 381,664,000	$ 375,781,000