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						$ (2,007)		(2,007)
Treasury stock purchased, shares						(212,080)
Cash dividends					(56,499)			(56,499)
Shares issued in employee stock purchase plan		599						599
Shares issued in employee stock purchase plan, shares	69,089
Stock-based compensation, net of forfeitures	$ 11	6,134						6,145
Stock-based compensation, net of forfeitures, shares	1,089,028					(108,917)
Shares issued for Elite acquisition	$ 217	225,663						225,880
Shares issued for Elite acquisition, shares	21,656,683
Comprehensive income (loss)
Net income (loss)					51,286			51,286
Interest rate swap gain (loss), net of reclassifications to earnings			(9,960)					(9,960)
Ending balance at Sep. 30, 2019	$ 1,586	3,410,378	(4,187)		(2,268,890)	$ (81,869)		1,057,018
Ending, shares at Sep. 30, 2019	158,602,309					(6,702,602)
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)
Comprehensive income (loss)
Accounting Standards Update [Extensible List]							us-gaap:AccountingStandardsUpdate201613Member
Ending balance at Dec. 31, 2019	$ 1,587	3,412,509	(1,387)	$ 166	(2,244,877)	$ (81,869)	$ 166	1,085,963
Ending, shares at Dec. 31, 2019	158,636,918					(6,702,602)
Beginning balance at Jun. 30, 2019	$ 1,369	3,182,247	(2,772)		(2,267,235)	$ (80,719)		832,890
Beginning, shares at Jun. 30, 2019	136,899,297					(6,577,558)
Increase (Decrease) in Stockholders' Equity
Treasury stock purchased						$ (1,150)		(1,150)
Treasury stock purchased, shares						(125,044)
Cash dividends					(22,062)			(22,062)
Shares issued in employee stock purchase plan		192						192
Shares issued in employee stock purchase plan, shares	20,288
Stock-based compensation, net of forfeitures		2,276						2,276
Stock-based compensation, net of forfeitures, shares	26,041
Shares issued for Elite acquisition	$ 217	225,663						225,880
Shares issued for Elite acquisition, shares	21,656,683
Comprehensive income (loss)
Net income (loss)					20,407			20,407
Interest rate swap gain (loss), net of reclassifications to earnings			(1,415)					(1,415)
Ending balance at Sep. 30, 2019	$ 1,586	3,410,378	(4,187)		(2,268,890)	$ (81,869)		1,057,018
Ending, shares at Sep. 30, 2019	158,602,309					(6,702,602)
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						$ (1,794)		(1,794)
Treasury stock purchased, shares						(235,079)
Cash dividends					(66,655)			(66,655)
Shares issued in employee stock purchase plan	$ 1	521						522
Shares issued in employee stock purchase plan, shares	140,606
Stock-based compensation, net of forfeitures	$ 11	8,616						8,627
Stock-based compensation, net of forfeitures, shares	1,193,832					(64,483)
Contribution from Exterran Corporation		678						678
Comprehensive income (loss)
Net income (loss)					(73,236)			(73,236)
Interest rate swap gain (loss), net of reclassifications to earnings			(4,586)					(4,586)
Ending balance at Sep. 30, 2020	$ 1,599	3,422,324	(5,973)		(2,384,602)	$ (83,663)		949,685
Ending, shares at Sep. 30, 2020	159,971,356					(7,002,164)
Beginning balance at Jun. 30, 2020	$ 1,598	3,419,512	(6,908)		(2,380,626)	$ (82,703)		950,873
Beginning, shares at Jun. 30, 2020	159,810,336					(6,860,984)
Increase (Decrease) in Stockholders' Equity
Treasury stock purchased						$ (960)		(960)
Treasury stock purchased, shares						(138,922)
Cash dividends					(22,308)			(22,308)
Shares issued in employee stock purchase plan		155						155
Shares issued in employee stock purchase plan, shares	30,351
Stock-based compensation, net of forfeitures	$ 1	2,657						2,658
Stock-based compensation, net of forfeitures, shares	130,669					(2,258)
Comprehensive income (loss)
Net income (loss)					18,332			18,332
Interest rate swap gain (loss), net of reclassifications to earnings			935					935
Ending balance at Sep. 30, 2020	$ 1,599	$ 3,422,324	$ (5,973)		$ (2,384,602)	$ (83,663)		$ 949,685
Ending, shares at Sep. 30, 2020	159,971,356					(7,002,164)