Share-Based Plans - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares
Options outstanding at beginning of period (in shares)	0	2,250	24,000
Granted (in Shares)	0
Exercised (in Shares)		(2,250)	(9,750)
Cancelled (in shares)			(12,000)
Options outstanding at end of period (in shares)		0	2,250
Exercisable at end of year (in shares)			2,250
Exercise Price
Options outstanding at beginning of year (in dollars per share)		$ 37.17	$ 38.39
Exercised		$ 37.17	37.17
Cancelled (in dollars per share)			39.60
Options outstanding at end of year (in dollars per share)			37.17
Exercisable at end of year			$ 37.17
Cash received from option exercise (in dollars)		$ 84	$ 362