Recent Accounting Developments - Balance Sheet Impact (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Accounts receivable, trade	$ 141,781	$ 121,299	$ 113,416
Inventory	77,497	83,774	90,691
Contract costs	36,482	21,524	0
Liabilities
Accrued liabilities	74,879	71,325	71,116
Deferred revenue	12,909	8,046	4,858
Deferred income taxes	2,845	102,370	97,943
Accounts payable, trade	70,950		54,585
Other long-term liabilities	19,612		20,116
Equity
Additional paid-in capital	3,154,058		3,093,058
Accumulated deficit	(2,259,489)	(2,226,577)	$ (2,241,243)
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Accounts receivable, trade	123,079
Inventory	94,528
Contract costs	0
Liabilities
Accrued liabilities	74,619
Deferred revenue	8,865
Deferred income taxes	2,570
Accounts payable, trade	70,875
Other long-term liabilities	19,595
Equity
Additional paid-in capital	3,144,217
Accumulated deficit	(2,283,130)
Adjustments Due to the Revenue Recognition Update | ASU 2014-09
Assets
Accounts receivable, trade	18,702	7,883
Inventory	(17,031)	(6,917)
Contract costs	36,482	21,524
Liabilities
Accrued liabilities	260	209
Deferred revenue	4,044	3,188
Deferred income taxes	275	4,427
Accounts payable, trade	75
Other long-term liabilities	17
Equity
Additional paid-in capital	9,841
Accumulated deficit	$ 23,641	$ 14,666