Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Regulated Operations [Abstract]

Summary of Composition of Regulatory Assets

Regulatory assets represent costs that are probable of recovery from customers in future rates. The majority of the regulatory assets earn a return. The following table summarizes the composition of regulatory assets as of December 31:

	2017		2016
Deferred pension expense	$	285	$	310
Income taxes recoverable through rates	—		241
Removal costs recoverable through rates	269		251
San Clemente Dam project costs	89		91
Regulatory balancing accounts	113		110
Debt expense	67		66
Make-whole premium on early extinguishment of debt	27		—
Purchase premium recoverable through rates	57		58
Deferred tank painting costs	42		39
Other	112		123
Total Regulatory Assets	$	1,061	$	1,289

Summary of Composition of Regulatory Liabilities

The following table summarizes the composition of regulatory liabilities as of December 31:

	2017		2016
Income taxes recovered through rates	$	1,242	$	—
Removal costs recovered through rates	315		316
Pension and other postretirement benefit balancing accounts	48		55
Other	59		32
Total Regulatory Liabilities	$	1,664	$	403