Net Income per Share - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Mar. 05, 2018	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Stock compensation expense		$ 0.6		$ 1.4
Common stock shares issued (in shares)		53,256,440		53,256,440	53,256,440
Common stock shares outstanding (in shares)		52,756,440		52,756,440	53,256,440
2016 Equity Plan
Class of Stock [Line Items]
Common stock shares issued (in shares)		150,715		150,715
Common stock shares outstanding (in shares)		152,807		152,807
Restricted Stock | 2017 Equity Plan
Class of Stock [Line Items]
Awards issued to employees and directors, unvested (in shares)		192,184		192,184
Phantom Share Units (PSUs) | 2016 and 2017 Equity Plans
Class of Stock [Line Items]
Settlement period				5 years
Phantom Share Units (PSUs) | 2016 Equity Plan
Class of Stock [Line Items]
Common stock shares contingently issuable (in shares)				43,580
Restricted Stock Units (RSUs) | 2017 Equity Plan
Class of Stock [Line Items]
Restricted stock unit awards awarded (in shares)	186,916
Common stock shares contingently issuable (in shares)				13,157
Common Stock | 2017 Equity Plan
Class of Stock [Line Items]
Common stock issued to employees and directors, vested (in shares)		99,895		99,895
August Equity Offering
Class of Stock [Line Items]
Incremental stock compensation expense				$ 3.6
Common Stock | August Equity Offering
Class of Stock [Line Items]
Stock issued during period (in shares)			13,000,000