Recent Accounting Developments - Balance Sheet Impact (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Accounts receivable, trade	$ 116,004	$ 121,299	$ 113,416
Inventory	84,208	83,774	90,691
Contract costs	26,718	21,524	0
Liabilities
Accrued liabilities	74,198	71,325	71,116
Deferred revenue	8,372	8,046	4,858
Deferred income taxes	102,539	102,370	97,943
Other long-term liabilities	20,498		20,116
Equity
Accumulated deficit	(2,238,800)	(2,226,577)	(2,241,243)
Noncontrolling interest	(44,407)		$ (41,431)
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Accounts receivable, trade	102,733
Inventory	95,554
Contract costs	0
Liabilities
Accrued liabilities	73,976
Deferred revenue	4,083
Deferred income taxes	97,408
Other long-term liabilities	20,492
Equity
Accumulated deficit	(2,256,316)
Noncontrolling interest	(45,886)
Adjustments Due to the Revenue Recognition Update | ASU 2014-09
Assets
Accounts receivable, trade	13,271	7,883
Inventory	(11,346)	(6,917)
Contract costs	26,718	21,524
Liabilities
Accrued liabilities	222	209
Deferred revenue	4,289	3,188
Deferred income taxes	5,131	4,427
Other long-term liabilities	6
Equity
Accumulated deficit	17,516	$ 14,666
Noncontrolling interest	$ 1,479