Stock-Based Compensation - Summary of Stock Options Outstanding (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Number of Shares
Beginning of period (in shares) | shares	2,121
Granted (in shares) | shares	188
Exercised (in shares) | shares	(68)
Forfeited (in shares) | shares	(5)
Expired (in shares) | shares	(2)
End of period (in shares) | shares	2,234
Weighted Average Exercise Price
Beginning of period (in dollars per share) | $ / shares	$ 31.53
Granted (in dollars per share) | $ / shares	40.49
Exercised (in dollars per share) | $ / shares	27.15
Forfeited (in dollars per share) | $ / shares	36.37
Expired (in dollars per share) | $ / shares	13.68
End of period (in dollars per share) | $ / shares	$ 32.42