Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 10,649	$ 7,028
Unrealized losses on securities:
Unrealized holding losses arising during period	(3,203)	(326)
Tax effect	1,221	124
Net of tax amount	(1,982)	(202)
Unrealized gains on derivative financial instruments qualifying as cash flow hedges:
Unrealized holding gains arising during period	29	41
Tax effect	(11)	(19)
Reclassification adjustment for amounts included in interest expense	73	71
Tax effect	(28)	(24)
Net of tax amount	63	69
Other comprehensive loss, net of tax	(1,919)	(133)
Comprehensive income	$ 8,730	$ 6,895