Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings per Share
Adjustments to net income (in dollars)	$ 0	$ 0	$ 0	$ 0
Antidilutive securities (in shares)	0	0	0	0
Numerator:
Net income	$ 56,895	$ 54,860	$ 113,635	$ 120,391
Denominator:
Basic: weighted-average shares outstanding (in shares)	139,546,615	139,459,620	139,546,174	139,459,620
Add: weighted-average equity-based awards (in shares)	99,502		98,383
Diluted: weighted-average shares outstanding (in shares)	139,646,117	139,459,620	139,644,557	139,459,620
Basic earnings per share (in dollars per share)	$ 0.41	$ 0.39	$ 0.81	$ 0.86
Diluted earnings per share (in dollars per share)	$ 0.41	$ 0.39	$ 0.81	$ 0.86