Regulatory Decision and Related Accounting and Policy Changes - Additional Information (Details) $ in Thousands		9 Months Ended	12 Months Ended
	Jul. 11, 2012 Utility	Sep. 30, 2016 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)	Jan. 01, 2010 USD ($)
Public Utilities General Disclosures [Line Items]
Number of utilities to adjust revenue requirement | Utility	7
Requested collective rate of increase over revenue	28.00%
Approved collective revenue increase		$ 3,600
Adopted rate of return on common equity		9.50%
Percentage of hook up fee liability to be recorded on ICFA receipts		70.00%
Percentage of deferred revenue to be recorded on ICFA receipts		30.00%
ICFA fee as deferred revenue		The Company is responsible for assuring the full HUF value is paid from ICFA proceeds, and recorded in its full amount, even if it results in recording less than 30% of the ICFA fee as deferred revenue.
Regulatory assets		$ 136		$ 227
Regulatory assets, amortization period		3 years
Intangible assets offset by regulatory liability					$ 11,200
Percentage reversal of regulatory liability			30.00%
Reversal of regulatory liability			$ 3,400
Percentage of regulatory liability		70.00%
Regulatory liability		$ 7,859		7,859
ICFA [Member]
Public Utilities General Disclosures [Line Items]
Deferred revenue		$ 19,700		$ 19,700