Supplemental Guarantor Financial Information - I/S (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Condensed Consolidated Statements of Comprehensive (Loss) Income
Revenues		$ 279,398	$ 351,507	$ 819,192	$ 1,010,598	$ 1,349,405
Operating costs and expenses				782,210
Loss (gain) on disposal and impairment of assets		814	637	1,847	3,101
Income from operations		22,133	31,378	35,135	67,241	86,434
Interest expense (income), net, including amortization of deferred financing costs and note discount				36,588
Loss on extinguishment of convertible notes	$ 3,000	0	0	3,018	0
Equity in earnings of subsidiaries				0
Other income				(9,651)
Income before income taxes		15,776	24,953	5,180	46,431
Income tax (benefit) expense		10,049	4,086	(4,375)	10,780
Net income (loss)		5,727	20,867	9,555	35,651	48,265
Net loss attributable to noncontrolling interests		(5)	3	(10)	(3)
Net income (loss) attributable to controlling interests and available to common shareholders		5,732	20,864	9,565	35,654	48,274
Other comprehensive loss attributable to controlling interest				(46,380)
Comprehensive (loss) income attributable to controlling interests		$ 20,333	$ 11,069	(36,815)	$ 8,925
Eliminations
Condensed Consolidated Statements of Comprehensive (Loss) Income
Revenues				(52,832)		(72,531)
Operating costs and expenses				(53,638)
Income from operations				806		300
Interest expense (income), net, including amortization of deferred financing costs and note discount				171
Loss on extinguishment of convertible notes				0
Equity in earnings of subsidiaries				42,259
Other income				(18,643)
Income before income taxes				(22,981)
Income tax (benefit) expense				0
Net income (loss)				(22,981)		(111,534)
Net loss attributable to noncontrolling interests				(10)
Net income (loss) attributable to controlling interests and available to common shareholders				(22,971)		(111,525)
Other comprehensive loss attributable to controlling interest				43,962
Comprehensive (loss) income attributable to controlling interests				20,991
Parent | Reportable Legal Entities
Condensed Consolidated Statements of Comprehensive (Loss) Income
Revenues				0		0
Operating costs and expenses				17,883
Income from operations				(17,883)		(35,637)
Interest expense (income), net, including amortization of deferred financing costs and note discount				0
Loss on extinguishment of convertible notes				0
Equity in earnings of subsidiaries				(25,929)
Other income				2,332
Income before income taxes				5,714
Income tax (benefit) expense				(3,841)
Net income (loss)				9,555		48,265
Net loss attributable to noncontrolling interests				0
Net income (loss) attributable to controlling interests and available to common shareholders				9,555		48,265
Other comprehensive loss attributable to controlling interest				(46,380)
Comprehensive (loss) income attributable to controlling interests				(36,825)
Issuer | Reportable Legal Entities
Condensed Consolidated Statements of Comprehensive (Loss) Income
Revenues				460,657		668,527
Operating costs and expenses				449,802
Loss (gain) on disposal and impairment of assets				919
Income from operations				9,936		40,733
Interest expense (income), net, including amortization of deferred financing costs and note discount				32,601
Loss on extinguishment of convertible notes				3,018
Equity in earnings of subsidiaries				(47,044)
Other income				9,418
Income before income taxes				11,943
Income tax (benefit) expense				(4,332)
Net income (loss)				16,275		20,546
Net loss attributable to noncontrolling interests				0
Net income (loss) attributable to controlling interests and available to common shareholders				16,275		20,546
Other comprehensive loss attributable to controlling interest				(37,161)
Comprehensive (loss) income attributable to controlling interests				(20,886)
Guarantors | Reportable Legal Entities
Condensed Consolidated Statements of Comprehensive (Loss) Income
Revenues				207,657		351,330
Operating costs and expenses				161,231
Loss (gain) on disposal and impairment of assets				227
Income from operations				46,199		70,835
Interest expense (income), net, including amortization of deferred financing costs and note discount				5,254
Loss on extinguishment of convertible notes				0
Equity in earnings of subsidiaries				30,432
Other income				5,915
Income before income taxes				4,598
Income tax (benefit) expense				6,259
Net income (loss)				(1,661)		63,952
Net loss attributable to noncontrolling interests				0
Net income (loss) attributable to controlling interests and available to common shareholders				(1,661)		63,952
Other comprehensive loss attributable to controlling interest				(2,169)
Comprehensive (loss) income attributable to controlling interests				(3,830)
Non-Guarantors | Reportable Legal Entities
Condensed Consolidated Statements of Comprehensive (Loss) Income
Revenues				203,710		402,079
Operating costs and expenses				206,932
Loss (gain) on disposal and impairment of assets				701
Income from operations				(3,923)		10,203
Interest expense (income), net, including amortization of deferred financing costs and note discount				(1,438)
Loss on extinguishment of convertible notes				0
Equity in earnings of subsidiaries				282
Other income				(8,673)
Income before income taxes				5,906
Income tax (benefit) expense				(2,461)
Net income (loss)				8,367		27,036
Net loss attributable to noncontrolling interests				0
Net income (loss) attributable to controlling interests and available to common shareholders				8,367		$ 27,036
Other comprehensive loss attributable to controlling interest				(4,632)
Comprehensive (loss) income attributable to controlling interests				$ 3,735