CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Comprehensive income:
Net income	$ 22,267us-gaap_NetIncomeLoss	$ 24,235us-gaap_NetIncomeLoss
Derivative instruments:
Reclassification of losses to net income, net of tax of $13 and $13, respectively	19	18
Other comprehensive income	19	18
Comprehensive income	$ 22,286us-gaap_ComprehensiveIncomeNetOfTax	$ 24,253us-gaap_ComprehensiveIncomeNetOfTax

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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