Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	$ 53,670	$ 54,083
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant and Equipment	(16,160)	(8,978)
Net Cash Used in Investing Activities	(16,160)	(8,978)
CASH FLOWS FROM FINANCING ACTIVITIES
Repayment of Credit Facility	(25,000)	(9,000)
Dividends Paid to Stockholders	(4,853)	(4,828)
Purchase and Retirement of Common Stock	(1,880)	(39,135)
Proceeds from Stock Option Exercises	1,273	10,632
Shares Redeemed to Settle Employee Taxes on Stock Compensation	(1,378)	(2,284)
Excess Tax Benefits from Share Based Payment Arrangements		3,299
Net Cash Used in Financing Activities	(31,838)	(41,316)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	5,672	3,789
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	6,561	5,391
CASH AND CASH EQUIVALENTS AT END OF PERIOD	12,233	9,180
Parent [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	16,506	(35,457)
CASH FLOWS FROM FINANCING ACTIVITIES
Repayment of Credit Facility	(25,000)	(9,000)
Dividends Paid to Stockholders	(4,853)	(4,828)
Purchase and Retirement of Common Stock	(1,880)	(39,135)
Proceeds from Stock Option Exercises	1,273	10,632
Shares Redeemed to Settle Employee Taxes on Stock Compensation	(1,378)	(2,284)
Excess Tax Benefits from Share Based Payment Arrangements		3,299
Intra-entity Activity, net	20,830	77,474
Net Cash Used in Financing Activities	(11,008)	36,158
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	5,498	701
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	5,184	3,507
CASH AND CASH EQUIVALENTS AT END OF PERIOD	10,682	4,208
Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities	37,164	89,540
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to Property, Plant and Equipment	(16,160)	(8,978)
Net Cash Used in Investing Activities	(16,160)	(8,978)
CASH FLOWS FROM FINANCING ACTIVITIES
Intra-entity Activity, net	(20,830)	(77,474)
Net Cash Used in Financing Activities	(20,830)	(77,474)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	174	3,088
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	1,377	1,884
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 1,551	$ 4,972