Leases - Schedule of Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Finance leases
Total	$ 495
Centuri
Operating leases
2020	10,394
2021	9,327
2022	8,328
2023	7,645
2024	5,710
Thereafter	31,303
Total lease payments	72,707
Less imputed interest	12,882
Total	59,825
Finance leases
2020	281
2021	128
2022	67
2023	38
2024	25
Thereafter	0
Total lease payments	539
Less imputed interest	44
Total	495
Southwest Gas Corporation
Operating leases
2020	800
2021	556
2022	295
2023	124
2024	78
Thereafter	307
Total lease payments	2,160
Less imputed interest	162
Total	$ 1,998