Significant Non-Cash Investing Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Other Significant Noncash Transactions [Line Items]
Outstanding receivables from outside parties for the funding of capital expenditures	$ 368,693		$ 375,993
Purchases of property and equipment accrued in accounts payable	10,700	$ 15,400
Accounts receivable - grants from outside parties [Member]
Other Significant Noncash Transactions [Line Items]
Outstanding receivables from outside parties for the funding of capital expenditures	$ 7,921	$ 13,700	$ 10,652