CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Comprehensive income:
Net income	$ 10,544	$ 5,742	$ 30,229	$ 20,620
Derivative instruments:
Reclassification of losses to net income, net of tax of $14, $12, $26 and $25, respectively	18	19	37	38
Other comprehensive income	18	19	37	38
Comprehensive income	$ 10,562	$ 5,761	$ 30,266	$ 20,658