Stock-Based Compensation - Summary of the Company's Service Based RSU Activity (Details) - RSUs - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of RSUs
Outstanding at the beginning of the period	500,000	500,000	500,000
Granted	100,000	100,000	100,000
Issued	(100,000)	(100,000)	(100,000)
Outstanding at the end of the period	490,739	500,000	500,000
Weighted-Average Grant Date Fair Value
Outstanding at the beginning of the period	$ 33.72	$ 31.73	$ 27.76
Granted	50.97	42.05	43.96
Issued	38.17	37.01	28.95
Outstanding at the end of the period	$ 36.75	$ 33.72	$ 31.73