New Accounting Pronouncements Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 37,521	$ 26,616
Restricted Cash and Cash Equivalents, Current	18,041	10,145
Other Comprehensive (Income) Loss, Reclassification of Stranded Taxes to Retained Earnings	5,200
Other Comprehensive Income (Loss) Reclassification of Stranded Taxes to RE for Pension Plans	5,230
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	55,562	36,761	$ 41,296	$ 50,443
Subsidiaries [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, at Carrying Value	35,452	25,864
Restricted Cash and Cash Equivalents, Current	18,041	10,145
Other Comprehensive (Income) Loss, Reclassification of Stranded Taxes to Retained Earnings	27,332
Other Comprehensive Income (Loss) Reclassification of Stranded Taxes to RE for Pension Plans	26,200
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	53,493	$ 36,009	$ 40,899	$ 49,805
Other Comprehensive Income (Loss) Reclassification of Stranded Taxes to RE for Interest Rate Swaps	$ 1,100