Capital Stock and Equity Awards - Summary of Option Activity (Details) - Options - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Shares
Beginning of period (in shares)	1,479,236	2,234,699
Granted (in shares)	0	195,509
Exercised (in shares)	(142,129)	(97,211)
Forfeited (in shares)	0	(50,062)
End of period (in shares)	1,337,107	2,282,935
Exercisable, end of period (in shares)	983,508	1,334,756
Weighted- Average Exercise Price
Beginning of period (in dollars per share)	$ 27.81	$ 22.84
Granted (in dollars per share)	0.00	42.17
Exercised (in dollars per share)	20.14	17.23
Forfeited (in dollars per share)	0.00	27.97
End of period (in dollars per share)	28.63	24.62
Exercisable, end of period (in dollars per share)	$ 26.06	$ 20.47
Vesting period (in years)	7 years
Minimum
Weighted- Average Exercise Price
Vesting period (in years)	3 years
Maximum
Weighted- Average Exercise Price
Vesting period (in years)	4 years