Lease Commitments - Schedule of Supplemental Cash Flows Related to Leases (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 27,225
Operating cash flows from financing leases	45
Finance cash flows from financing leases	189
Non-cash information related to right-of-use assets obtained in exchange for lease obligations:
Operating leases	157,816
Financing leases	7,402
PNM
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	26,092
Operating cash flows from financing leases	28
Finance cash flows from financing leases	113
Non-cash information related to right-of-use assets obtained in exchange for lease obligations:
Operating leases	143,816
Financing leases	3,645
TNMP
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	757
Operating cash flows from financing leases	17
Finance cash flows from financing leases	72
Non-cash information related to right-of-use assets obtained in exchange for lease obligations:
Operating leases	12,942
Financing leases	$ 3,678