Regulatory and Rate Matters (Tables)

3 Months Ended

Mar. 31, 2019

Regulated Operations [Abstract]

Schedule of Rate Increases for Transmission Costs

The following sets forth TNMP’s recent interim transmission cost rate increases:

Effective Date	Approved Increase in Rate Base		Annual Increase in Revenue
	(In millions)
September 8, 2016	$	9.5	$	1.8
March 14, 2017	30.2		4.8
September 13, 2017	27.5		4.7
March 27, 2018	32.0		0.6
March 21, 2019	111.8		14.3