Related Parties (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Aggregate summarized financial information
Sales and merchandising revenues	$ 1,297,830	$ 938,660	$ 1,338,167	$ 1,001,674	$ 1,153,969	$ 706,825	$ 810,999	$ 721,998	$ 4,576,331	$ 3,393,791	$ 3,025,304
Gross profit	86,431	64,964	122,772	78,685	82,466	53,109	87,554	58,550	352,852	281,679	255,506
Net income									96,825	64,881	39,566
Current assets	1,107,222				1,138,558				1,107,222	1,138,558
Current liabilities	794,251				836,743				794,251	836,743
Noncontrolling interest	538,842				464,559				538,842	464,559	406,276	365,107
Subsidiaries [Member]
Aggregate summarized financial information
Sales and merchandising revenues									6,938,345	4,707,422	3,436,192
Gross profit									168,383	133,653	106,755
Income from continuing operations									90,510	59,046	37,439
Net income									87,673	57,691	37,757
Current assets	707,400				697,371				707,400	697,371
Non-current assets	336,554				352,441				336,554	352,441
Current liabilities	514,617				550,463				514,617	550,463
Non-current liabilities	100,315				115,735				100,315	115,735
Noncontrolling interest	$ 26,799				$ 31,294				$ 26,799	$ 31,294