Stock Compensation Plans - Schedule of Stock Option Activity and Weighted Average Exercise Prices (Details) - Employee Stock Option $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Options
Outstanding at January 1, 2016 (in shares) | shares	1,090,160
Granted (in shares) | shares	267,794
Forfeited (in shares) | shares	(84,591)
Exercised (in shares) | shares	(96,212)
Unearned performance-based options (in shares) | shares	(20,388)
Outstanding at December 31, 2016 (in shares) | shares	1,156,763
Options exercisable at December 31, 2016 | shares	914,941
Weighted- Average Exercise Price
Outstanding at January 1, 2017 (in dollars per share) | $ / shares	$ 48.02
Granted (in dollars per share) | $ / shares	34.75
Forfeited (in dollars per share) | $ / shares	44.39
Exercised (in dollars per share) | $ / shares	37.05
Unearned performance-based options (in dollars per share) | $ / shares	59.97
Outstanding at December 31, 2017 (in dollars per share) | $ / shares	45.93
Options exercisable at December 31, 2017 (in dollars per share) | $ / shares	$ 42.20
Weighted-Average Remaining Contractual Term (Years)
Weighted-average remaining contractual term in years outstanding at December 31, 2017	4 years 3 months 18 days
Weighted-average remaining contractual term in years options exercisable at December 31, 2017	2 years 3 months 18 days
Aggregate Intrinsic Value as of December 31, 2017
Aggregate intrinsic value outstanding at December 31, 2017 | $	$ 7,082
Aggregate intrinsic value of options exercisable at December 31, 2017 | $	$ 2,369