Capital Stock and Equity Awards - Summary of Option Activity (Details) - Options - $ / shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Shares
Beginning of period (in shares)	2,234,699	2,058,085
Granted (in shares)	205,244	706,203
Exercised (in shares)	(443,114)	(231,916)
Forfeited (in shares)	(50,062)	(3,362)
End of period (in shares)	1,946,767	2,529,010
Exercisable, end of period (in shares)	992,395	1,017,643
Weighted- Average Exercise Price
Beginning of period (in dollars per share)	$ 22.84	$ 18.11
Granted (in dollars per share)	42.24	32.07
Exercised (in dollars per share)	18.72	15.95
Forfeited (in dollars per share)	27.97	21.00
End of period (in dollars per share)	25.69	22.20
Exercisable, end of period (in dollars per share)	$ 20.95	$ 17.01