Financial Information Related to Guarantor Subsidiaries (Details Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.01	$ 0.01
Parent [Member]
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.01	$ 0.01
Issuer [Member]
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.01	$ 0.01
Guarantor Subsidiaries [Member]
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.01	$ 0.01
Non-Guarantor Subsidiaries [Member]
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.01	$ 0.01
Eliminations [Member]
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Preferred stock, par value	$ 0.01	$ 0.01
Unsecured senior notes due 2019 [Member]
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Unsecured senior notes, issued	$ 500
Stated interest rate on unsecured senior notes	6.375%
Unsecured senior notes due 2021 [Member]
Financial Information Related to Guarantor Subsidiaries (Textual) [Abstract]
Unsecured senior notes, issued	$ 800
Stated interest rate on unsecured senior notes	7.125%