Business Segments Information - Schedule of Revenue from Reportable Segments by Product Type (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Total Net sales	$ 358,359	$ 357,576
Domestic [Member]
Segment Reporting Information [Line Items]
Total Net sales	319,497	312,763
Domestic [Member] | Pipe [Member]
Segment Reporting Information [Line Items]
Total Net sales	226,191	223,310
Domestic [Member] | Allied Products [Member]
Segment Reporting Information [Line Items]
Total Net sales	93,306	89,453
International Segment [Member]
Segment Reporting Information [Line Items]
Total Net sales	38,862	44,813
International Segment [Member] | Pipe [Member]
Segment Reporting Information [Line Items]
Total Net sales	29,769	34,372
International Segment [Member] | Allied Products [Member]
Segment Reporting Information [Line Items]
Total Net sales	$ 9,093	$ 10,441