Segment Information (Schedule of Revenue by Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues	$ 155,681	$ 174,027	$ 141,495	$ 127,896	$ 137,989	$ 174,475	$ 128,747	$ 134,125	$ 599,099	$ 575,336	$ 606,950
United States
Revenues									597,899	573,398	601,738
Canada
Revenues									173	851	2,618
Mexico
Revenues									$ 1,027	919	$ 2,594
Other
Revenues										$ 168