Earnings per Share - Narrative (Details) - shares	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Warrants outstanding (in shares)	50,025,000	50,025,000	50,025,000	50,025,000
Founders Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	12,476,250	12,476,250	12,476,250	12,476,250
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	25,012,500	25,012,500	25,012,500	25,012,500