Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net services revenue ($141.9 million and $278.1 million for the three and six months ended June 30, 2018, respectively, and $87.7 million and $163.1 million for the three and six months ended June 30, 2017, respectively, from related party)	$ 207.9	$ 99.4	$ 355.2	$ 186.3
Operating expenses:
Cost of services	189.9	96.4	328.6	177.3
Selling, general and administrative	22.5	12.2	39.5	26.5
Other	13.2	1.0	15.6	1.2
Total operating expenses	225.6	109.6	383.7	205.0
Income (loss) from operations	(17.7)	(10.2)	(28.5)	(18.7)
Net interest (expense) income	(5.8)	0.0	(5.6)	0.1
Income (loss) before income tax provision	(23.5)	(10.2)	(34.1)	(18.6)
Income tax provision (benefit)	(20.6)	(3.5)	(7.9)	(3.6)
Net income (loss)	$ (2.9)	$ (6.7)	$ (26.2)	$ (15.0)
Net income (loss) per common share:
Basic (in dollars per share)	$ (0.07)	$ (0.11)	$ (0.33)	$ (0.23)
Diluted (in dollars per share)	$ (0.07)	$ (0.11)	$ (0.33)	$ (0.23)
Weighted average shares used in calculating net income (loss) per common share:
Basic (in shares)	108,157,583	102,467,078	107,001,002	101,918,797
Diluted (in shares)	108,157,583	102,467,078	107,001,002	101,918,797
Consolidated statements of comprehensive income (loss)
Net income (loss)	$ (2.9)	$ (6.7)	$ (26.2)	$ (15.0)
Other comprehensive income (loss):
Net change on derivatives designated as cash flow hedges, net of tax	(0.4)	0.0	(0.6)	0.0
Foreign currency translation adjustments	(1.4)	0.0	(1.9)	0.8
Comprehensive income (loss)	(4.7)	(6.7)	(28.7)	(14.2)
Basic:
Net income (loss)	(2.9)	(6.7)	(26.2)	(15.0)
Less dividends on preferred shares	(4.8)	(4.4)	(9.4)	(8.7)
Less income allocated to preferred shareholders	0.0	0.0	0.0	0.0
Net income (loss) available/(allocated) to common shareholders - basic	(7.7)	(11.1)	(35.6)	(23.7)
Diluted:
Net (loss) income	(2.9)	(6.7)	(26.2)	(15.0)
Less dividends on preferred shares	(4.8)	(4.4)	(9.4)	(8.7)
Less income allocated to preferred shareholders	0.0	0.0	0.0	0.0
Net income (loss) available/(allocated) to common shareholders - diluted	$ (7.7)	$ (11.1)	$ (35.6)	$ (23.7)