Business Segments Information - Schedule of Revenue from Reportable Segments by Product Type (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Net Sales	$ 508,639	$ 413,708
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	508,639	413,708
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net Sales	(19,913)
Pipe Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	271,807	262,181
Pipe Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	273,652	262,181
Pipe Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net Sales	(1,845)
Infiltrator Water Technologies Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	84,085
Infiltrator Water Technologies Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	102,153
Infiltrator Water Technologies Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net Sales	(18,068)
International Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	35,829	39,333
International Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	35,829	39,333
International Segment [Member] | Pipe [Member]
Segment Reporting Information [Line Items]
Net Sales	26,950	29,284
International Segment [Member] | Pipe [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	26,950	29,284
International Segment [Member] | Allied Products and Other [Member]
Segment Reporting Information [Line Items]
Net Sales	8,879	10,049
International Segment [Member] | Allied Products and Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	8,879	10,049
Allied Products and Other [Member]
Segment Reporting Information [Line Items]
Net Sales	116,918	112,194
Allied Products and Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 116,918	$ 112,194