Interim Consolidated Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interim Consolidated Financial Information (Unaudited)
Revenues	$ 789,509	$ 620,643	$ 688,043	$ 568,507	$ 579,389	$ 551,581	$ 529,932	$ 497,857	$ 2,666,702	$ 2,158,759	$ 1,881,883
Net income (loss)	$ 149,850	$ (15,203)	$ 290,298	$ (720,642)	$ 111,005	$ 128,271	$ 105,318	$ 102,312	$ (295,697)	$ 446,906	$ 109,493
Basic net income (loss) per share	$ 0.68	$ (0.07)	$ 1.33	$ (3.33)	$ 0.51	$ 0.60	$ 0.49	$ 0.48	$ (1.36)	$ 2.08	$ 0.52
Diluted net income (loss) per share	$ 0.68	$ (0.07)	$ 1.32	$ (3.33)	$ 0.51	$ 0.59	$ 0.48	$ 0.47	$ (1.36)	$ 2.05	$ 0.51
Shares used in computation of basic net income (loss) per share	219,239	218,784	217,549	216,721	215,770	215,199	214,620	214,065	218,073	214,913	212,383
Shares used in computation of diluted net income (loss) per share	221,228	218,784	220,434	216,721	218,542	217,791	217,483	217,061	218,073	217,657	215,635