Stock-Based Compensation Narrative (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement [Line Items]
Compensation expense	$ 1,510	$ 734
Stock-based compensation expense, net of tax benefit	$ 1,049	$ (10)
Directors' Plan [Member]
Statement [Line Items]
Shares reserved for future grants under the stock option and compensation plan	360
Employee Equity Plan [Member]
Statement [Line Items]
Awards vesting period (in years)	3 years
Shares reserved for future grants under the stock option and compensation plan	11,100