Stock-Based Compensation - Schedule of stock option activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Shares, Options outstanding, Beginning of period (in shares)	34,343
Number of Shares, Granted (in shares)	0
Number of Shares, Exercised (in shares)	(34,343)
Number of Shares, Cancelled (in shares)	0
Number of Shares, Options outstanding, End of period (in shares)	0	34,343
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted Average Exercise Price, Options outstanding, Beginning of period (in dollars per share)	$ 8.12
Weighted Average Exercise Price, Granted (in dollars per share)	0.00
Weighted Average Exercise Price, Exercised (in dollars per share)	8.12
Weighted Average Exercise Price, Cancelled (in dollars per share)	0.00
Weighted Average Exercise Price, Options outstanding, End of period (in dollars per share)	$ 0.00	$ 8.12
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Terms (Years), Options outstanding	0 years	11 months
Aggregate Intrinsic Value, Options outstanding	$ 0.0	$ 1.0