Related Parties - Assets and Liabilities (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
ASSETS
Accounts receivable	[1]	$ 107,506	$ 75,667
Prepaid expenses - current	[1]	25,449	28,488
Customer advance for regulatory capital requirements	[1]	39,955	40,000
Prepaid expenses and other noncurrent assets	[1]	5,801	6,253
Liabilities
Accounts payable	[1]	80,035	37,488
Accrued liabilities	[1]	28,203	33,343
Affiliated Entity
ASSETS
Accounts receivable		12,058	8,781
Prepaid expenses - current		1,552	1,592
Customer advance for regulatory capital requirements		39,955	40,000
Prepaid expenses and other noncurrent assets		44,761	2,709
Liabilities
Accounts payable		6,867	6,429
Accrued liabilities		5,322	2,583
Reserve for claims and performance-based arrangements		$ 1,037	$ 4,264

[1] See Note 18 for amounts attributable to related parties included in these line items.