Revenue (Summary of Impact of Change in Accounting Principle on Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Contract revenues in excess of billings	$ 17,953	$ 77,907
Other current assets	31,907	38,605
Other	10,760	13,088
LIABILITIES AND EQUITY
Accrued expenses	(48,351)	(51,926)
Billings in excess of contract revenues	17,793	2,586
Deferred taxes	(22,846)	(25,561)
Accumulated deficit	(74,971)	$ (67,101)
ASU 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
ASSETS
Contract revenues in excess of billings	(18,334)
Other current assets	8,953
Other	4,176
LIABILITIES AND EQUITY
Accrued expenses	(5,306)
Billings in excess of contract revenues	5,834
Deferred taxes	(1,468)
Accumulated deficit	$ (4,265)