Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements of Comprehensive Income [Abstract]
Taxes (benefit) on unrealized gain (loss)	$ 140	$ (91)
Taxes (benefits) on reclassification adjustment	$ 8	$ 3