SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)(Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Selected quarterly financial information
Total revenues	$ 1,190,640	$ 1,706,310	$ 1,326,759	$ 1,037,247	$ 990,770	$ 1,452,804	$ 1,102,716	$ 809,320	$ 5,260,956	$ 4,355,610	$ 3,084,905
Gross profit	939,750	1,396,501	1,004,142	743,288	724,697	1,100,148	749,227	505,808	4,083,681	3,079,880	1,908,971
Net income	289,595	599,973	352,654	181,816	225,955	472,886	256,277	104,013	1,424,037	1,059,131	528,142
Net income applicable to common stockholders	$ 288,663	$ 596,586	$ 352,347	$ 181,970	$ 225,715	$ 469,499	$ 256,368	$ 104,790
Net income applicable to common stockholders per basic common share (in dollars per share)	$ 5.79	$ 11.97	$ 7.07	$ 3.65	$ 4.53	$ 9.43	$ 5.16	$ 2.12	$ 28.48	$ 21.27	$ 11.00
Net income applicable to common stockholders per diluted common share (in dollars per share)	$ 5.63	$ 11.66	$ 6.88	$ 3.54	$ 4.41	$ 9.17	$ 5.02	$ 2.05	$ 27.66	$ 20.63	$ 10.35