Stock-Based Compensation - Stock Appreciation Rights (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares
NUMBER OF SHARES
Granted (in shares) | shares	57,851
WEIGHTED AVERAGE EXERCISE PRICE
Granted (in dollars per share)	$ 43.40
Stock Appreciation Rights (SARs)
NUMBER OF SHARES
Beginning balance (in shares) | shares	91,000
Exercised (in shares) | shares	0
Canceled (in shares) | shares	(19,445)
Stock exercisable (in shares) | shares	18,000
WEIGHTED AVERAGE EXERCISE PRICE
Beginning balance (in dollars per share)	$ 53.75
Exercised (in dollars per share)	0
Canceled (in dollars per share)	50.87
Ending balance (in dollars per share)	49.55
Stock exercisable (in dollars per share)	$ 54.19
WEIGHTED AVERAGE REMAINING CONTRACTUAL LIFE (YEARS)
Stock outstanding, weighted average remaining contractual life	4 years 1 month 6 days
Stock exercisable, weighted average remaining contractual life	3 years 8 months 12 days
AGGREGATE INTRINSIC VALUE
Stock outstanding | $	$ 0
Stock exercisable | $	$ 0