Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance at Sep. 30, 2017	$ 696,261	$ 771	$ 894,089	$ (178,015)	$ (20,584)
Balance, Shares at Sep. 30, 2017		77,083
Net loss	(2,740)			(2,740)
Other comprehensive income (loss), net of tax	7,996				7,996
Capital contributions and issuance of common stock	99		99
Capital contributions and issuance of common stock, Shares		12
Equity-based compensation	5,802		5,802
Repurchase of common stock and distributions	(2,804)	$ (1)	(2,803)
Repurchase of common stock and distributions, Shares		(110)
Reclassification of effects of tax reform enactment				3,466	(3,466)
Balance at Mar. 31, 2018	704,614	$ 770	897,187	(177,289)	(16,054)
Balance, Shares at Mar. 31, 2018		76,985
Balance at Dec. 31, 2017	720,063	$ 771	895,242	(155,225)	(20,725)
Balance, Shares at Dec. 31, 2017		77,065
Net loss	(22,064)			(22,064)
Other comprehensive income (loss), net of tax	4,671				4,671
Capital contributions and issuance of common stock, Shares		6
Equity-based compensation	4,276		4,276
Repurchase of common stock and distributions	(2,332)	$ (1)	(2,331)
Repurchase of common stock and distributions, Shares		(86)
Balance at Mar. 31, 2018	704,614	$ 770	897,187	(177,289)	(16,054)
Balance, Shares at Mar. 31, 2018		76,985
Balance at Sep. 30, 2018	1,227,327	$ 1,045	1,426,344	(189,636)	(10,426)
Balance, Shares at Sep. 30, 2018		104,470
Net loss	(12,433)			(12,433)
Other comprehensive income (loss), net of tax	(1,358)				(1,358)
Capital contributions and issuance of common stock	1	$ 5	(4)
Capital contributions and issuance of common stock, Shares		492
Equity-based compensation	11,519		11,519
Adoption of ASU No. 2014-09 (Refer to Note 2) | Accounting Standards Update 2014-09	(1,092)			(1,092)
Balance at Mar. 31, 2019	1,223,964	$ 1,050	1,437,859	(203,161)	(11,784)
Balance, Shares at Mar. 31, 2019		104,962
Balance at Dec. 31, 2018	1,220,826	$ 1,050	1,432,247	(199,555)	(12,916)
Balance, Shares at Dec. 31, 2018		104,962
Net loss	(3,606)			(3,606)
Other comprehensive income (loss), net of tax	1,132				1,132
Equity-based compensation	5,612		5,612
Balance at Mar. 31, 2019	$ 1,223,964	$ 1,050	$ 1,437,859	$ (203,161)	$ (11,784)
Balance, Shares at Mar. 31, 2019		104,962