Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Components of comprehensive income:
Net income	$ 177,127	$ 146,120	$ 331,456	$ 293,612
Other comprehensive income	0	0	0	0
Total comprehensive income	$ 177,127	$ 146,120	$ 331,456	$ 293,612