Revenue Recognition - Additional information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Basic earnings per share	$ 0.49	$ 0.39	$ 1.23	$ (0.24)
Diluted earnings per share	$ 0.48	0.38	$ 1.22	$ (0.24)
Adoption of ASC Topic 606
Disaggregation Of Revenue [Line Items]
Cumulative effect on retained earnings, before tax			$ 4.7
Cumulative effect on retained earnings, net of tax			$ 3.5
Basic earnings per share		0.39
Net loss per share			$ 0.24
Adoption of ASC Topic 606 | As Reported
Disaggregation Of Revenue [Line Items]
Basic earnings per share		0.38
Net loss per share			$ 0.25
Adoption of ASC Topic 606 | ASC 606 Adjustments
Disaggregation Of Revenue [Line Items]
Diluted earnings per share		$ 0