General - Accounts Receivable, Contract Assets and Contract Liabilities - Tabular Disclosure (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Summary of Significant Accounting Policies
Accounts receivable	$ 837,710	$ 717,455
Change in accounts receivable	$ 120,255
Change in accounts receivable (as a percent)	16.80%
Contract assets	$ 7,151	2,162
Change in contract assets	$ (4,989)
Change in contract assets (as a percent)	230.80%
Contract liabilities - current	$ 25,769	6,728
Change in contract liabilities - current	$ 19,041
Change in contract liabilities - current (as a percent)	283.00%
Contract liabilities - long-term	$ 11,022	$ 11,099
Change in contract liabilities - long-term	$ (77)
Change in contract liabilities - long-term (as a percent)	(0.70%)