Schedule of Intangible Assets, Including Impact of Impairment Charges (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Cost	$ 582,523	$ 554,565
Intangible Assets, Accumulated Amortization	(104,805)	(96,406)
Goodwill, Cost	392,569	380,711
Goodwill, Additions	77,325	11,858
Goodwill, Net	469,894	392,569
Goodwill and Intangible Assets, Additions	118,034	27,958
Goodwill and Intangible Assets, net	$ 595,752	$ 486,117
Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life		25 years
Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life		40 years
Customer Contracts And Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life	15 years	15 years
Intangible Assets, Cost	$ 157,294	$ 141,194
Intangible Assets, Additions	40,209	16,100
Intangible Assets, Accumulated Amortization	(89,444)	(82,077)
Intangible Assets, Net	108,059	75,217
Permits [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Cost	30,760	30,760
Intangible Assets, Additions	0	0
Intangible Assets, Accumulated Amortization	(14,358)	(13,413)
Intangible Assets, Net	$ 16,402	$ 17,347
Permits [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life	25 years
Permits [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life	40 years
Trade Name [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life	15 years	15 years
Intangible Assets, Cost	$ 1,900	$ 1,900
Intangible Assets, Additions	500	0
Intangible Assets, Accumulated Amortization	(1,003)	(916)
Intangible Assets, Net	$ 1,397	$ 984