Business and Summary of Significant Accounting Principles Business and Summary of Significant Accounting Principles (Revenue Recognition) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Public Utilities, General Disclosures [Line Items]
Revenues	$ 231,098	$ 231,089
Receivables	223,898		$ 208,384
High Cost Support Program [Member]
Public Utilities, General Disclosures [Line Items]
Revenues	16,200	$ 17,300
Receivables	$ 45,300