Consolidated Statements of Income and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Interest income:
Loans and loans held for sale	$ 103,005	$ 108,417	$ 309,213	$ 330,877
Investment securities:
Taxable	20,633	21,949	64,834	65,610
Tax-exempt	3,844	3,189	11,270	9,521
Total investment securities interest	24,477	25,138	76,104	75,131
Total interest income	127,482	133,555	385,317	406,008
Deposits:
Demand-interest bearing	243	218	726	579
Savings and money market accounts	5,166	6,929	15,302	22,172
Certificates and other time deposits	2,743	4,370	9,436	16,803
Securities sold under agreements to repurchase	310	977	854	2,832
Wholesale borrowings	1,130	1,669	3,399	4,963
Total interest expense	9,592	14,163	29,717	47,349
Net interest income	117,890	119,392	355,600	358,659
Provision for noncovered loan losses	9,965	14,604	26,860	41,760
Provision for covered loan losses	6,214	4,768	15,576	17,580
Net interest income after provision for loan losses	101,711	100,020	313,164	299,319
Other income:
Trust department income	6,124	5,607	17,481	16,983
Service charges on deposits	14,603	17,838	43,490	48,460
Credit card fees	11,006	13,640	32,402	39,357
ATM and other service fees	3,680	3,801	11,360	9,781
Bank owned life insurance income	3,094	3,182	9,073	11,439
Investment services and insurance	2,208	1,965	6,843	6,384
Investment securities gains, net	553	4,402	1,361	5,291
Loan sales and servicing income	7,255	3,426	19,085	9,102
Other operating income	6,402	6,911	20,857	18,222
Total other income	54,925	60,772	161,952	165,019
Other expenses:
Salaries, wages, pension and employee benefits	58,061	61,232	183,632	177,815
Net occupancy expense	8,077	8,464	24,640	25,144
Equipment expense	7,143	7,073	21,845	20,725
Stationery, supplies and postage	2,210	2,517	6,638	7,972
Bankcard, loan processing and other costs	8,424	8,449	24,935	24,278
Professional services	4,702	5,732	17,361	17,466
Amortization of intangibles	456	543	1,422	1,629
FDIC expense	1,832	3,240	9,015	12,187
Other operating expense	17,682	18,707	51,944	53,254
Total other expenses	108,587	115,957	341,432	340,470
Income before income tax expense	48,049	44,835	133,684	123,868
Income tax expense	13,096	13,098	37,802	34,808
Net income	34,953	31,737	95,882	89,060
Other comprehensive income (loss), net of taxes:
Changes in unreaized securities' holding gains and losses	4,884	7,353	10,872	24,889
Reclassification for realized securities' gains	(359)	(2,862)	(885)	(3,440)
Total other comprehensive gain (loss), net of taxes	4,525	4,491	9,987	21,449
Comprehensive income	39,478	36,228	105,869	110,509
Net income available to common shareholders	34,953	31,737	95,882	89,060
Net income used in diluted EPS calculation	$ 34,953	$ 31,737	$ 95,882	$ 89,060
Weighted average number of common shares outstanding - basic	109,645	109,245	109,473	109,052
Average common shares outstanding	109,645	109,246	109,473	109,053
Basic earnings per common share (in dollars per share)	$ 0.32	$ 0.29	$ 0.88	$ 0.82
Diluted earnings per common share (in dollars per share)	$ 0.32	$ 0.29	$ 0.88	$ 0.82
Dividend per common share (in dollars per share)	$ 0.16	$ 0.16	$ 0.48	$ 0.48
Non stock options [Member]
Other comprehensive income (loss), net of taxes:
Average common shares outstanding			109,473	109,053