Related Party Transactions (Summarized Financial Information of Company's Equity Method Investees) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Sales and merchandising revenues	$ 1,885,603	$ 1,982,755	$ 2,325,041	$ 1,976,792	$ 812,662	$ 685,579	$ 911,402	$ 635,739	$ 8,170,191	$ 3,045,382	$ 3,686,345
Gross profit	138,359	109,141	160,728	109,664	93,962	53,864	90,474	63,705	517,892	302,005	318,799
Net income	5,667	$ (5,870)	$ 29,411	$ (14,148)	23,669	$ (1,875)	$ 21,413	$ (1,982)	15,060	41,225	42,609
Current assets	1,945,342				1,023,198				1,945,342	1,023,198
Current liabilities	1,439,919				833,350				1,439,919	833,350
Noncontrolling interests	1,195,655				876,764				1,195,655	876,764	822,899	$ 790,697
Subsidiaries
Related Party Transaction [Line Items]
Sales and merchandising revenues									1,930,289	6,111,036	6,080,795
Gross profit									39,253	257,594	217,629
Income from continuing operations									1,895	71,608	50,937
Net income									940	68,876	42,970
Current assets	255,052				1,111,826				255,052	1,111,826	1,045,124
Non-current assets	80,823				526,169				80,823	526,169	538,671
Current liabilities	196,163				792,184				196,163	792,184	802,161
Non-current liabilities	$ 31,509				$ 281,103				$ 31,509	$ 281,103	$ 309,649