Consolidated Statements of Comprehensive Income (Parenthetical) (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated Statements of Comprehensive Income [Abstract]
Taxes (benefits) on unrealized gain (loss)	$ 188	$ (146)	$ 354	$ (143)
Taxes (benefits) on reclassification adjustment	$ 2		$ 12	$ 3