Nature of Operations and Basis of Consolidation (Details) $ in Millions	Mar. 31, 2017 USD ($) watts	Dec. 31, 2016 customers
Number of customers \| customers		709,600
Number of megawatts of qualifying facility \| watts	35
Estimated aggregate gross contractual payments for qualifying facilities through 2024 \| $	$ 239.7

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

No definition available.

Name:	us-gaap_ContractualObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant