Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Statement of Income and Comprehensive Income [Abstract]
Net Income	$ 279,658	$ 270,776	$ 280,357
Equity interest in unrealized gain (loss) on interest rate hedge	(519)	891	369
Total Comprehensive Income	$ 279,139	$ 271,667	$ 280,726