New Accounting Pronouncements Adoption of 606 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Services	$ 393,662	$ 375,830	$ 379,743	$ 326,968	$ 402,747	$ 375,800	$ 390,532	$ 344,700	$ 1,476,203	$ 1,513,779	$ 1,385,785
Earnings Per Share, Basic and Diluted									$ (2.31)
Cost of Goods and Services Sold	$ 256,088	$ 238,690	$ 253,390	$ 243,030	$ 268,673	$ 249,418	$ 267,822	$ 237,563	$ 991,198	1,023,476	936,133
Operating Income (Loss)									9,696	131,959	48,431
Net Income (Loss) Available to Common Stockholders, Basic									(132,088)	$ 205,594	$ (45,839)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Services									$ 1,527,839
Earnings Per Share, Basic and Diluted									$ (2.43)
Cost of Goods and Services Sold									$ 1,053,556
Operating Income (Loss)									(1,026)
Net Income (Loss) Available to Common Stockholders, Basic									(138,971)
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Services									$ 51,636
Earnings Per Share, Basic and Diluted									$ (0.12)
Cost of Goods and Services Sold									$ 62,358
Operating Income (Loss)									(10,722)
Net Income (Loss) Available to Common Stockholders, Basic									$ (6,883)