Selected Income Statement Information Selected Income Statement Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Services	$ 1,509,786	$ 2,001,167	$ 2,336,304
Products	761,817	1,061,587	1,323,320
Total revenue	2,271,603	3,062,754	3,659,624
Cost of Services and Products:
Services	1,330,218	1,585,305	1,742,411
Products	615,438	800,316	946,923
Unallocated expenses	46,720	71,704	111,089
Total cost of services and products	1,992,376	2,457,325	2,800,423
Gross margin:
Services	179,568	415,862	593,893
Products	146,379	261,271	376,397
Unallocated expenses	(46,720)	(71,704)	(111,089)
Gross Margin	$ 279,227	$ 605,429	$ 859,201