Summary of Accounting Policies Summary of Effect of Adoption on Consolidated Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Item Effected [Line Items]
Accrued revenue	$ 20,747		$ 27,499
Regulated Energy Operating Revenue	103,618	$ 109,393
Regulated Energy cost of sales	36,516	48,231
Depreciation and amortization	11,074	9,704
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	38,238	36,810
Income taxes	9,574	9,955
Net Income	28,664	$ 26,855
Other assets	5,197		6,985
Retained earnings	$ 284,111		$ 261,530