General - Accounts Receivable, Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2018	Jan. 01, 2018
General
Accounts receivable	$ 864,674	$ 864,674	$ 679,269
Change in accounts receivable (in dollars)		$ 185,405
Change in accounts receivable (as a percent)		27.30%
Contract assets	14,339	$ 14,339	8,564
Change in contract assets (in dollars)		$ 5,775
Change in contract assets (as a percent)		67.40%
Contract liabilities - current	75,552	$ 75,552	14,299
Change in contract liabilities - current (in dollars)		$ 61,253
Change in contract liabilities - current (as a percent)		428.40%
Contract liabilities - long-term	12,612	$ 12,612	$ 12,303
Change in contract liabilities - long-term (in dollars)		$ 309
Change in contract liabilities - long-term (as a percent)		2.50%
Revenue recognized previously included in current contract liabilities	59,200	$ 70,500
Estimated revenue to be recognized in 2018	70,900	70,900
Estimated revenue to be recognized in 2019	6,100	6,100
Estimated revenue to be recognized in 2020	2,600	2,600
Estimated revenue to be recognized in 2021 and beyond	$ 8,600	$ 8,600

The aggregate of amounts due from customers or clients for goods or services that have been delivered or sold in the normal course of business and an amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection and net of any write-downs taken for collection uncertainty on the part of the holder, respectively.

No definition available.