Significant Non-Cash Investing Activities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Other Significant Noncash Transactions [Line Items]
Outstanding receivables from outside parties for the funding of capital expenditures	$ 457,225		$ 436,360
Purchases of property and equipment accrued in accounts payable	22,300	$ 9,200
Accounts receivable - grants from outside parties [Member]
Other Significant Noncash Transactions [Line Items]
Outstanding receivables from outside parties for the funding of capital expenditures	$ 18,748	$ 10,900	$ 19,376