Share-Based Compensation - Stock Option Activity (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Number of Options (in thousands)
Outstanding beginning balance (in shares) | shares	3,610
Granted (in shares) | shares	493
Exercised (in shares) | shares	(575)
Outstanding ending balance (in shares) | shares	3,528
Weighted Average Exercise Price per Option
Outstanding beginning balance (in dollars per share) | $ / shares	$ 46.44
Granted (in dollars per share) | $ / shares	76.16
Exercised (in dollars per share) | $ / shares	38.71
Outstanding ending balance (in dollars per share) | $ / shares	$ 51.86