Investment in Equity Affiliate (Details) - USD ($) number in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	[1],[2]	Dec. 31, 2016	[1],[2]	Dec. 12, 2017
Schedule of Equity Method Investments [Line Items]
Loss from equity-method investment	$ 0	$ 247,000	$ 0		$ 0
Corridor
Schedule of Equity Method Investments [Line Items]
Aggregate cost							$ 3,000,000
Ownership interest							0.00%

[1] Adjusted pursuant to adoption of ASU 2016-18, Statements of Cash Flows, Restricted Cash. Refer to Note 8 and Note 27 to the consolidated financial statements.

[2] Adjusted pursuant to adoption of ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-retirement Benefit Cost. Refer to Note 21 and Note 27 to the consolidated financial statements.