Contractual Commitments, Contingencies and Off-Balance Sheet Arrangements - Additional Information (Details) $ in Millions	1 Months Ended		6 Months Ended
	Mar. 31, 2015 term	Mar. 31, 2014 term	Dec. 31, 2018 USD ($)
Contractual Commitments Contingencies And Off- Balance Sheet Arrangements [Line Items]
Payment to acquire equity method investment			$ 1.8
Remaining capital commitment			1.8
IT Services Agreement
Contractual Commitments Contingencies And Off- Balance Sheet Arrangements [Line Items]
IT service agreement extension term	2 years
Number of renewal terms option one | term	1
Renewal term option one (in months)	12 months
Remaining capital commitment			320.2
EU IT Services Agreement
Contractual Commitments Contingencies And Off- Balance Sheet Arrangements [Line Items]
Number of renewal terms option one | term		1
Renewal term option one (in months)		12 months
Number of renewal terms option two | term		1
Renewal term option two (in months)		24 months
Remaining capital commitment			$ 25.2