Stock-Based Compensation - Summary of PSU Activity (Details) - Performance-based Stock Units	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Units
Balance at the beginning of the period (in shares) | shares	0
Granted (in shares) | shares	30,071
Balance at the end of the period (in shares) | shares	30,071
Weighted-Average Grant-Date Fair Value
Balance at the beginning of the period (in dollars per share) | $ / shares	$ 0.00
Granted (in dollars per share) | $ / shares	83.84
Balance at the end of the period (in dollars per share) | $ / shares	$ 83.84