Summarized Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summarized Quarterly Data (Unaudited)
Net revenues	$ 769,036	$ 806,247	$ 796,463	$ 776,224	$ 742,910	$ 765,597	$ 769,422	$ 756,451	$ 3,147,970	$ 3,034,380	$ 2,838,358
Income (loss) from operations	26,775	143,663	134,989	140,287	113,848	139,300	149,337	140,531	445,714	543,016	467,846
Net income (loss)	$ (338,060)	$ 789,340	$ 17,079	$ 5,104	$ 5,032	$ 46,535	$ 34,035	$ 23,708	$ 473,463	$ 109,310	$ 686
Basic earnings per common share (in dollars per share)	$ (3.72)	$ 8.68	$ 0.19	$ 0.06	$ 0.06	$ 0.52	$ 0.38	$ 0.26	$ 5.21	$ 1.21	$ 0.01
Diluted earnings per common share (in dollars per share)	$ (3.72)	$ 8.43	$ 0.18	$ 0.06	$ 0.05	$ 0.51	$ 0.37	$ 0.26	$ 5.07	$ 1.19	$ 0.01