Stock-Based Compensation - Summary of the Company's PRSU Activity (Details) - PRSUs - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of PRSUs
Outstanding at the beginning of the period	400,000	400,000	400,000
Granted	200,000	200,000	100,000
Additional performance shares		100,000	100,000
Issued	(200,000)	(300,000)	(200,000)
Outstanding at the end of the period	367,760	400,000	400,000
Weighted-Average Grant Date Fair Value
Outstanding at the beginning of the period	$ 42.66	$ 36.59	$ 31.68
Granted	50.50	43.96	43.96
Additional performance shares		28.09	42.23
Issued	42.57	28.15	24.95
Outstanding at the end of the period	$ 45.35	$ 42.66	$ 36.59