Business Segments (Financial Information For Segments Of Corporation) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Interest income	$ 107,756	$ 98,702	$ 324,328	$ 294,228
Interest expense	14,225	18,300	45,395	57,849
Net interest income	93,531	80,402	278,933	236,379
Provision for loan losses	8,429	8,573	22,028	25,352
Non-interest income	34,813	29,630	99,336	87,320
Non-interest expense	74,840	67,409	235,345	206,734
Intangible amortization	2,242	1,808	6,892	5,409
Income tax expense (benefit)	12,090	8,469	32,549	22,894
Net income (loss)	30,743	23,773	81,455	63,310
Total assets	11,984,891	9,951,344	11,984,891	9,951,344	9,786,483
Total intangibles	717,263	600,283	717,263	600,283
Community Banking [Member]
Segment Reporting Information [Line Items]
Interest income	97,364	88,291	293,756	264,281
Interest expense	10,912	14,798	35,130	46,910
Net interest income	86,452	73,493	258,626	217,371
Provision for loan losses	6,826	7,005	17,215	20,653
Non-interest income	25,048	22,033	72,904	62,840
Non-interest expense	61,820	55,562	196,510	169,938
Intangible amortization	2,056	1,617	6,334	4,838
Income tax expense (benefit)	11,456	8,230	31,882	22,561
Net income (loss)	29,342	23,112	79,589	62,221
Total assets	11,803,432	9,755,499	11,803,432	9,755,499
Total intangibles	693,029	575,300	693,029	575,300
Wealth Management [Member]
Segment Reporting Information [Line Items]
Interest income		3	4	9
Net interest income		3	4	9
Non-interest income	6,006	5,653	17,889	17,959
Non-interest expense	4,844	4,402	14,587	13,984
Intangible amortization	80	84	240	251
Income tax expense (benefit)	396	426	1,117	1,344
Net income (loss)	686	744	1,949	2,389
Total assets	19,075	19,869	19,075	19,869
Total intangibles	11,392	11,716	11,392	11,716
Insurance [Member]
Segment Reporting Information [Line Items]
Interest income	27	31	85	97
Net interest income	27	31	85	97
Non-interest income	3,602	3,143	10,072	9,702
Non-interest expense	2,947	2,842	8,658	8,905
Intangible amortization	106	107	318	320
Income tax expense (benefit)	204	82	420	208
Net income (loss)	372	143	761	366
Total assets	19,281	18,435	19,281	18,435
Total intangibles	11,033	11,458	11,033	11,458
Consumer Finance [Member]
Segment Reporting Information [Line Items]
Interest income	8,860	8,662	25,888	25,224
Interest expense	869	1,053	2,736	3,234
Net interest income	7,991	7,609	23,152	21,990
Provision for loan losses	1,421	1,353	4,218	4,337
Non-interest income	590	509	1,674	1,580
Non-interest expense	4,829	4,411	14,016	13,116
Income tax expense (benefit)	888	896	2,530	2,348
Net income (loss)	1,443	1,458	4,062	3,769
Total assets	170,304	171,312	170,304	171,312
Total intangibles	1,809	1,809	1,809	1,809
Parent and Other [Member]
Segment Reporting Information [Line Items]
Interest income	1,505	1,715	4,595	4,617
Interest expense	2,444	2,449	7,529	7,705
Net interest income	(939)	(734)	(2,934)	(3,088)
Provision for loan losses	182	215	595	362
Non-interest income	(433)	(1,708)	(3,203)	(4,761)
Non-interest expense	400	192	1,574	791
Income tax expense (benefit)	(854)	(1,165)	(3,400)	(3,567)
Net income (loss)	(1,100)	(1,684)	(4,906)	(5,435)
Total assets	$ (27,201)	$ (13,771)	$ (27,201)	$ (13,771)