Stock-Based Compensation - Summary of Changes in Number of Shares of Restricted Stock and Restricted Stock Units (Details)	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Shares
Shares outstanding, beginning of period (in shares) | shares	174,000
Granted (in shares) | shares	199,000
Vested (in shares) | shares	(120,000)
Canceled (in shares) | shares	(43,000)
Shares outstanding, end of period (in shares) | shares	210,000
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, beginning of period (in dollars per share) | $ / shares	$ 190.73
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	247.68
Weighted average grant date fair value, vested (in dollars per share) | $ / shares	202.59
Weighted average grant date fair value, canceled (in dollars per share) | $ / shares	220.58
Weighted average grant date fair value, end of period (in dollars per share) | $ / shares	$ 242.46