Consolidated Statements of Income and Comprehensive Income (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Interest income:
Loans and loans held for sale	$ 438,393,000	$ 433,763,000	$ 340,236,000
Investment securities:
Taxable	87,044,000	95,527,000	106,265,000
Tax-exempt	12,819,000	13,080,000	13,026,000
Total investment securities interest	99,863,000	108,607,000	119,291,000
Total interest income	538,256,000	542,370,000	459,527,000
Deposits:
Demand-interest bearing	816,000	751,000	600,000
Savings and money market accounts	28,171,000	31,912,000	23,472,000
Certificates and other time deposits	20,003,000	32,713,000	54,610,000
Securities sold under agreements to repurchase	3,344,000	4,477,000	4,764,000
Wholesale borrowings	6,295,000	13,998,000	27,317,000
Total interest expense	58,629,000	83,851,000	110,763,000
Net interest income	479,627,000	458,519,000	348,764,000
Provision for noncovered loan losses	54,035,000	83,783,000	98,433,000
Provision for covered loan losses	20,353,000	4,432,000	0
Net interest income after provision for loan losses	405,239,000	370,304,000	250,331,000
Other income:
Trust department income	22,396,000	21,951,000	20,683,000
Service charges on deposits	64,082,000	65,900,000	63,366,000
Credit card fees	49,539,000	49,010,000	46,512,000
ATM and other service fees	13,701,000	11,259,000	11,110,000
Bank owned life insurance income	14,820,000	14,949,000	13,740,000
Investment services and insurance	8,228,000	9,451,000	10,008,000
Investment securities gains, net	11,081,000	855,000	6,037,000
Loan sales and servicing income	14,533,000	19,440,000	12,954,000
Gain on George Washington acquisition	0	1,041,000	0
Gain on post medical retirement curtailment	0	0	9,543,000
Other operating income	26,377,000	18,700,000	16,348,000
Total other income	224,757,000	212,556,000	210,301,000
Other expenses:
Salaries, wages, pension and employee benefits	240,362,000	221,316,000	175,906,000
Net occupancy expense	32,414,000	32,665,000	24,099,000
Equipment expense	27,959,000	27,664,000	24,301,000
Stationery, supplies and postage	10,691,000	11,438,000	8,907,000
Bankcard, loan processing and other costs	32,226,000	31,572,000	31,467,000
Professional services	23,229,000	29,357,000	16,414,000
Amortization of intangibles	2,172,000	2,914,000	347,000
FDIC expense	17,306,000	17,790,000	16,510,000
Other operating expense	77,986,000	68,144,000	54,866,000
Total other expenses	464,345,000	442,860,000	352,817,000
Income before income tax expense	165,651,000	140,000,000	107,815,000
Income tax expense	46,093,000	37,091,000	25,645,000
Net income	119,558,000	102,909,000	82,170,000
Other comprehensive income (loss), net of taxes:
Changes in unrealized securities' holding gains and losses	26,205,000	(555,000)	38,994,000
Reclassification for realized securities' gains	(7,203,000)	(556,000)	(3,924,000)
Unrealized hedging gain (loss)		0	(94,000)
Change in minimum pension liability	(16,786,000)	467,000	(6,355,000)
Total other comprehensive gain (loss), net of taxes	2,216,000	(644,000)	28,621,000
Comprehensive income	121,774,000	102,265,000	110,791,000
Net income available to common shareholders	119,558,000	102,909,000	75,799,000
Net income used in diluted EPS calculation	119,558,000	102,909,000	75,799,000
Weighted average number of common shares outstanding - basic	109,102	101,163	84,678
Average common shares outstanding		101,165	84,686
Basic earnings per common share (in dollars per share)	$ 1.10	$ 1.02	$ 0.90
Diluted earnings per common share (in dollars per share)	$ 1.10	$ 1.02	$ 0.90
Stock dividend per common share (in dollars per share)	$ 0.00	$ 0.00	$ 0.01
Dividend per common share (in dollars per share)	$ 0.64	$ 0.64	$ 0.77