Debt - Additional Information 7 (Detail) (USD $)	1 Months Ended				1 Months Ended	3 Months Ended			1 Months Ended	3 Months Ended
	Apr. 18, 2013	Mar. 31, 2013	Dec. 31, 2012	Apr. 24, 2009	Jul. 13, 2012 5.75% Notes [Member]	Mar. 31, 2013 5.75% Notes [Member] D	Mar. 31, 2013 5.75% Notes [Member] Minimum [Member]	Mar. 31, 2013 5.75% Notes [Member] Maximum [Member]	Sep. 28, 2012 5.625% Senior Notes [Member]	Mar. 31, 2013 5.625% Senior Notes [Member] D	Mar. 31, 2013 5.625% Senior Notes [Member] Minimum [Member]	Mar. 31, 2013 5.625% Senior Notes [Member] Maximum [Member]
Line of Credit Facility [Line Items]
Unsecured senior notes		$ 5,430,247,000	$ 5,440,073,000		$ 800,000,000				$ 500,000,000
Interest rate for senior notes					5.75%				5.625%	5.625%
Interest payable dates					July 15 and January 15				October 1 and April 1
Debt instrument, maturity date	May 01, 2013				Jul. 15, 2020				Oct. 01, 2019
Deferred financing fees				$ 7,700,000	$ 13,900,000				$ 8,400,000
Payment of additional interest							0.25%	1.00%			0.25%	1.00%
Period of payment of additional interest						90				90