Condensed Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 97,114	$ 67,000	$ 242,820	$ 169,555
Unrealized gain (loss) on interest rate derivative instruments, net of deferred tax expense (benefit) of ($320), $0, ($511) and $0	(553)	0	(909)	0
Other comprehensive income (loss)	(553)	0	(909)	0
Comprehensive income	$ 96,561	$ 67,000	$ 241,911	$ 169,555