Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other Comprehensive Income [Abstract]
Unrealized gains on available-for-sale securities, taxes	$ 6,061	$ (561)	$ 6,761	$ (730)
Other Comprehensive Income Loss Reclassification Adjustment For Sale Or Writedown Of Securities Included In Net Income Tax	188	171	325	321
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Tax, Including Portion Attributable to Noncontrolling Interest, Available-for-sale Securities	$ 0	$ (2)	$ 0	$ 0