Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Comprehensive Income [Abstract]
Unrealized gains on available-for-sale securities, taxes	$ (1,256)	$ (3,206)	$ 855
Other Comprehensive Income Loss Reclassification Adjustment For Sale Or Writedown Of Securities Included In Net Income Tax	364	189	212
Other Than Temporary Impairment Losses recognized in earnings, tax	0	(345)	(553)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Available-for-sale Securities	$ 0	$ 31	$ 1,103