Acquisitions (Textual) (Details) (USD $)			0 Months Ended				0 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 07, 2012 Independent Bank [Member] Branches	Apr. 30, 2010 OAK [Member] Offices	Dec. 31, 2012 OAK [Member]	Dec. 31, 2011 OAK [Member]	Apr. 30, 2010 Stock Options [Member] OAK [Member]	Dec. 31, 2010 Stock Options [Member] OAK [Member]	Dec. 31, 2012 Core deposit intangible assets [Member] Independent Bank [Member]	Dec. 07, 2012 Core deposit intangible assets [Member] Independent Bank [Member]	Dec. 31, 2011 Core deposit intangible assets [Member] Independent Bank [Member]
Business Acquisition [Line Items]
Number of branches acquired (branches)			21
Deposits acquired			$ 404,000,000
Loans acquired			44,000,000
Acquisition purchase price			8,100,000	83,700,000
Premium paid on deposits purchased			11,500,000
Premium paid as a percent of deposits purchased (percent)			2.85%
Discount on loans purchased (percent)			1.75%
Goodwill	120,164,000	113,414,000	6,800,000	43,500,000
Intangibles acquired			5,600,000	9,800,000					5,600,000	5,600,000	0
Stock issued during acquisition (shares)				3,529,772
Stock issued during acquisition, value				83,700,000
Share price				$ 23.70
Number of options issued in OAK acquistion							26,425	26,425
Fair value of OAK vested stock options				41,000
Cash paid In lieu of fractional shares				8,000
Vested stock option conversion ratio							1.306
Shares of OAK stock purchased				2,703,009
Service provided by acquiree bank through number of branches				14
Assets of acquiree company				820,000,000
Loans of acquiree company				627,000,000
Deposits of acquiree company				693,000,000
Brokered deposits of acquiree company				193,000,000
Contractually required principal and interest payments of loan portfolio				683,000,000
Contractually required interest payments of loan portfolio				97,000,000
Expected principal cash flows of contractually required acquired loan portfolio				636,000,000
Expected interest cash flows of contractually required acquired loan portfolio				88,000,000
Expected interest cash flows of contractually required loan portfolio fair value				627,000,000
Nonaccretable difference				56,000,000
Expected credit losses				47,000,000
Accretable yield				97,000,000
Outstanding contractual principal balance of acquired loan portfolio					419,000,000	530,000,000
Carrying amount of acquired loan portfolio					$ 393,000,000	$ 493,000,000