Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Consolidated Statements of Comprehensive Income
Net income	$ 1,610	$ 3,289
Derivative instruments
Unrealized gain (loss) on derivative instruments	9	(2,300)
Reclassification adjustment for losses included in net income	366	2,448
Net gain recognized in other comprehensive income	375	148
Tax expense related to items of other comprehensive income	(137)	(54)
Other comprehensive income	238	94
Total comprehensive income	$ 1,848	$ 3,383