Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Comprehensive Income [Abstract]
Net Income	$ 23,349	$ 22,209	$ 21,118
Other Comprehensive Income (Loss)
Increase (Decrease) in Net Unrealized Gains on Available-for-Sale Securities	4,182	5,364	(2,525)
Reclassification Adjustment for Realized Gains on Available-for-Sale Securities Included in Net Income	(158)	(95)	(2,895)
Deferred Tax (Expense) Benefit	(1,692)	(2,215)	2,279
Change in Net Unrealized Gains on Available-for-Sale Securities, Net of Tax	2,332	3,054	(3,141)
Total Other Comprehensive Income (Loss)	2,332	3,054	(3,141)
Comprehensive Income	$ 25,681	$ 25,263	$ 17,977