Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income	$ 107,769	$ 140,545	$ 266,062	$ 257,244
Other comprehensive income, net of tax:
Change in value of derivatives	21	21	63	82
Other comprehensive income	21	21	63	82
Comprehensive income	$ 107,790	$ 140,566	$ 266,125	$ 257,326