Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets

The amounts recorded as regulatory assets and liabilities in the Consolidated Balance Sheets as of December 31, 2017 and 2016, are summarized in the table below. The table also includes amounts related to unamortized debt expense and unamortized discount on long-term debt, while not regulatory assets and liabilities, are a critical component of the embedded cost of debt financing utilized in Texas Gas' rate proceedings. The tax effect of the equity component of AFUDC represents amounts recoverable from rate payers for the tax recorded in regulatory accounting. Certain amounts in the table are reflected as a negative, or a reduction, to be consistent with the regulatory books of account. The period of recovery for the regulatory assets included in rates varies from one to eighteen years. The remaining period of recovery for regulatory assets not yet included in rates would be determined in future rate proceedings. None of the regulatory assets shown below were earning a return as of December 31, 2017 and 2016 (in millions):

	2017		2016
Regulatory Assets:
Pension	$	10.6	$	10.6
Tax effect of AFUDC equity	2.3		2.7
Total regulatory assets	$	12.9	$	13.3

Schedule of Regulatory Liabilities

Regulatory Liabilities:
Cashout and fuel tracker	$	0.4		$	10.1
Provision for other asset retirement	65.8			63.7
Unamortized debt expense and premium on reacquired debt	(5.6		)	(6.8		)
Unamortized discount on long-term debt	(0.8		)	(1.0		)
Postretirement benefits other than pension	48.9			45.9
Total regulatory liabilities	$	108.7		$	111.9