Equity - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Number of Stock Options [Roll Forward]
Outstanding at December 31, 2017 (in shares) | shares	4,013,388
Granted (in shares) | shares	522,881
Exercised (in shares) | shares	(170,536)
Outstanding at March 31, 2018 (in shares) | shares	4,365,733
Weighted Average Exercise Price Per Option [Abstract]
Outstanding at December 31, 2017 (in dollars per share) | $ / shares	$ 41.13
Granted (in dollars per share) | $ / shares	67.00
Exercised (in dollars per share) | $ / shares	23.03
Outstanding at March 31, 2018 (in dollars per share) | $ / shares	$ 44.93