Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Components of other intangible assets and related amortization
Gross Carrying Amount	$ 243,022	$ 28,600
Accumulated Amortization	31,947	15,397
Net Carrying Amount	211,075	13,203
Core deposit intangibles [Member]
Components of other intangible assets and related amortization
Gross Carrying Amount	206,047	25,747
Accumulated Amortization	27,691	13,218
Net Carrying Amount	178,356	12,529
Credit card and trust relationships [Member]
Components of other intangible assets and related amortization
Gross Carrying Amount	22,400
Accumulated Amortization	1,908
Net Carrying Amount	20,492
Value of insurance business acquired [Member]
Components of other intangible assets and related amortization
Gross Carrying Amount	2,431	2,431
Accumulated Amortization	1,926	1,757
Net Carrying Amount	505	674
Non-compete agreements [Member]
Components of other intangible assets and related amortization
Gross Carrying Amount	322	322
Accumulated Amortization	322	322
Net Carrying Amount	0	0
Trade name [Member]
Components of other intangible assets and related amortization
Gross Carrying Amount	11,822	100
Accumulated Amortization	100	100
Net Carrying Amount	$ 11,722	$ 0