Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 1,200	$ 1,300
Goodwill [Line Items]
Goodwill	191,371	$ 191,307	$ 191,371	$ 191,307
Non Strategic [Member]
Goodwill [Line Items]
Gross goodwill	200,000		200,000
Accumulated impairments	114,100		114,100
Accumulated divestiture related write-offs	85,900		85,900
Goodwill	$ 0		$ 0