Stock-Based Incentive Plans - Stock Option Activity (Details) - Non-Qualified Stock Options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Shares
Exercisable at the start of the period (in shares)	251
Exercised (in shares)	(44)
Forfeited (in shares)	0
Exercisable at the end of the period (in shares)	207	251
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average exercise price at beginning of the period (in dollars per share)	$ 29.66
Weighted-average exercise price at end of the period (in dollars per share)	$ 29.66	$ 29.66
Weighted-average remaining contractual life	7 months 18 days	1 year 1 month 12 days
Outstanding at the end of the period (in dollars)	$ 2,913	$ 3,558
Closing price per share (in dollars per share)	$ 43.71