CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Deficit	Treasury Stock	Cumulative Effect, Period of Adoption, Adjustment	Total
Beginning balance at Dec. 31, 2018	$ 1,358	$ 3,177,982	$ 5,773		$ (2,263,677)	$ (79,862)		$ 841,574
Beginning, shares at Dec. 31, 2018	135,787,509					(6,381,605)
Increase (Decrease) in Stockholders' Equity
Treasury stock purchased						$ (857)		(857)
Treasury stock purchased, shares						(87,036)
Cash dividends					(34,437)			(34,437)
Shares issued in employee stock purchase plan		407						407
Shares issued in employee stock purchase plan, shares	48,801
Stock-based compensation, net of forfeitures	$ 11	3,858						3,869
Stock-based compensation, net of forfeitures, shares	1,062,987					(108,917)
Comprehensive income (loss)
Net income (loss)					30,879			30,879
Interest rate swap gain (loss), net of reclassifications to earnings			(8,545)					(8,545)
Ending balance at Jun. 30, 2019	$ 1,369	3,182,247	(2,772)		(2,267,235)	$ (80,719)		832,890
Ending, shares at Jun. 30, 2019	136,899,297					(6,577,558)
Beginning balance at Mar. 31, 2019	$ 1,369	3,180,546	2,548		(2,261,452)	$ (80,719)		842,292
Beginning, shares at Mar. 31, 2019	136,876,352					(6,484,075)
Increase (Decrease) in Stockholders' Equity
Cash dividends					(17,206)			(17,206)
Shares issued in employee stock purchase plan		189						189
Shares issued in employee stock purchase plan, shares	19,073
Stock-based compensation, net of forfeitures		1,512						1,512
Stock-based compensation, net of forfeitures, shares	3,872					(93,483)
Comprehensive income (loss)
Net income (loss)					11,423			11,423
Interest rate swap gain (loss), net of reclassifications to earnings			(5,320)					(5,320)
Ending balance at Jun. 30, 2019	$ 1,369	3,182,247	(2,772)		(2,267,235)	$ (80,719)		832,890
Ending, shares at Jun. 30, 2019	136,899,297					(6,577,558)
Beginning balance at Dec. 31, 2019	$ 1,587	3,412,509	(1,387)	$ 166	(2,244,877)	$ (81,869)	$ 166	1,085,963
Beginning, shares at Dec. 31, 2019	158,636,918					(6,702,602)
Increase (Decrease) in Stockholders' Equity
Treasury stock purchased						$ (834)		(834)
Treasury stock purchased, shares						(96,157)
Cash dividends					(44,347)			(44,347)
Shares issued in employee stock purchase plan	$ 1	366						367
Shares issued in employee stock purchase plan, shares	110,255
Stock-based compensation, net of forfeitures	$ 10	5,959						5,969
Stock-based compensation, net of forfeitures, shares	1,063,163					(62,225)
Contribution from Exterran Corporation		678						678
Comprehensive income (loss)
Net income (loss)					(91,568)			(91,568)
Interest rate swap gain (loss), net of reclassifications to earnings			(5,521)					(5,521)
Ending balance at Jun. 30, 2020	$ 1,598	3,419,512	(6,908)		(2,380,626)	$ (82,703)		950,873
Ending, shares at Jun. 30, 2020	159,810,336					(6,860,984)
Beginning balance at Mar. 31, 2020	$ 1,598	3,415,784	(7,173)		(2,328,069)	$ (82,668)		999,472
Beginning, shares at Mar. 31, 2020	159,756,498					(6,830,407)
Increase (Decrease) in Stockholders' Equity
Treasury stock purchased						$ (35)		(35)
Treasury stock purchased, shares						(5,563)
Cash dividends					(22,176)			(22,176)
Shares issued in employee stock purchase plan		165						165
Shares issued in employee stock purchase plan, shares	53,838
Stock-based compensation, net of forfeitures		2,885						2,885
Stock-based compensation, net of forfeitures, shares						(25,014)
Contribution from Exterran Corporation		678						678
Comprehensive income (loss)
Net income (loss)					(30,381)			(30,381)
Interest rate swap gain (loss), net of reclassifications to earnings			265					265
Ending balance at Jun. 30, 2020	$ 1,598	$ 3,419,512	$ (6,908)		$ (2,380,626)	$ (82,703)		$ 950,873
Ending, shares at Jun. 30, 2020	159,810,336					(6,860,984)