Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other Comprehensive Income [Abstract]
Unrealized gains on available-for-sale securities, taxes	$ (1,066)	$ (1,189)	$ (1,796)	$ (3,386)
Other Comprehensive Income Loss Reclassification Adjustment For Sale Or Writedown Of Securities Included In Net Income Tax	43	(118)	364	(67)
Unrealized gains (losses) on available-for-sale securities for which a portion of an other-than-temporary impairment has been recognized in income, taxes	$ 0	$ 0	$ 0	$ 0