Incentive Stock Plans - Schedule of Stock Option Activity (Details) - Stock Options $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Number of Shares
Number of Shares, Beginning Balance | shares	1,079,800
Granted (in shares) | shares	0
Exercised (in shares) | shares	(229,006)
Cancelled or expired (in shares) | shares	(9,728)
Number of Shares, Ending Balance | shares	841,066
Number of Shares, Options exercisable | shares	841,066
Weighted Average Exercise Price (per common share)
Weighted Average Exercise Price (in dollars per common share), Beginning Balance | $ / shares	$ 28.16
Granted (in dollars per share) | $ / shares	0.00
Exercised (in dollars per share) | $ / shares	20.75
Cancelled or expired (in dollars per share) | $ / shares	33.00
Weighted Average Exercise Price (in dollars per common share), Ending Balance | $ / shares	30.13
Weighted Average Exercise Price (in dollars per common share), Options exercisable | $ / shares	$ 30.13
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual term (in years), Options outstanding	4 years 2 months 12 days
Weighted Average Remaining Contractual term (in years), Options exercisable	4 years 2 months 12 days
Aggregate Intrinsic Value, Options outstanding | $	$ 2,589
Aggregate Intrinsic Value, Options exercisable | $	$ 2,589