Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Goodwill [Roll Forward]
Beginning balance, January 1	$ 22,577	$ 0
Acquired	14,056	22,577
Ending balance, September 30	36,633	22,577
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	59,347		57,220
Accumulated Amortization	43,193		38,148
Net Carrying Amount	16,154		19,072
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2013	1,793
2014	3,669
2015	2,628
2016	1,486
2017	1,352
2018	1,236
Core deposit intangibles [Member]
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	57,547		55,420
Accumulated Amortization	42,943		38,029
Net Carrying Amount	14,604		17,391
Other [Member]
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	1,800		1,800
Accumulated Amortization	250		119
Net Carrying Amount	$ 1,550		$ 1,681