Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data (Unaudited)
Total revenue	$ 1,416,260	$ 1,302,256	$ 1,236,563	$ 1,215,058	$ 1,344,431	$ 1,228,617	$ 1,188,066	$ 1,118,969	$ 5,170,138	$ 4,880,084	$ 4,306,432
Operating Income	692,546	600,565	564,890	557,689	614,598	564,953	524,327	516,721	2,415,689	2,220,600	1,943,154
Consolidated net income	449,304	367,293	400,525	334,468	370,496	306,371	260,936	781,829	1,551,590	1,719,632	1,245,900
Net income attributable to common stockholders	$ 381,555	$ 311,675	$ 339,936	$ 283,138	$ 315,383	$ 254,921	$ 215,445	$ 645,410	$ 1,316,304	$ 1,431,159	$ 1,021,462
Net income (loss) per share - Basic	$ 1.23	$ 1.00	$ 1.10	$ 0.91	$ 1.01	$ 0.84	$ 0.71	$ 2.18	$ 4.24	$ 4.72	$ 3.48
Net income (loss) per share - Diluted	$ 1.23	$ 1.00	$ 1.10	$ 0.91	$ 1.01	$ 0.84	$ 0.71	$ 2.18	$ 4.24	$ 4.72	$ 3.48
Weighted average shares outstanding (in shares)	310,434,337	310,332,777	310,261,278	309,986,506	303,137,350	304,107,489	303,252,359	295,693,410	310,255,168	303,137,350	293,504,064
Diluted weighted average shares outstanding (in shares)	310,434,337	310,332,777	310,261,278	309,986,709	303,138,422	304,108,559	303,253,401	295,694,520	310,255,218	303,138,422	293,573,472