Debt (Details) - USD ($)	3 Months Ended				6 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	May 02, 2016
Debt, Long-term and Short-term, Combined Amount [Abstract]
Total debt	$ 386,098,000	$ 387,833,000			$ 386,098,000
Revolving line of credit	33,881,000	33,881,000			33,881,000
Current maturities	0	(2,000,000)			0
Total long-term debt	386,098,000	385,833,000			386,098,000
Amortization of financing and debt discount		(1,000,000)			(800,000)
Interest expense
Contractual interest expense	9,688,000		$ 9,784,000		19,398,000	$ 19,570,000
Capitalized interest	(51,000)		(236,000)		(103,000)	(276,000)
Amortization of debt issuance costs	348,000		348,000		696,000	696,000
Amortization of debt (premium) discount	(200,000)		(185,000)		(399,000)	(366,000)
Imputed interest on acquisition-related obligations	40,000		54,000		81,000	107,000
Interest expense on capital lease	85,000		46,000		160,000	93,000
Total interest expense	9,910,000		$ 9,811,000		19,833,000	19,824,000
Line of Credit Facility [Abstract]
Additional Borrowings					0
Repayments					0	$ 3,500,000
10.5% Senior Notes, net [Member]
Debt, Long-term and Short-term, Combined Amount [Abstract]
Total debt	352,217,000	353,952,000			$ 352,217,000
Amortization of financing and debt discount	$ (783,000)			$ (1,047,000)
Line of Credit Facility [Abstract]
Rate	10.50%				10.50%
Long-term Debt, Unclassified [Abstract]
Repayments of debt					$ 2,000,000
Long-term debt outstanding	$ 353,000,000	354,999,000			353,000,000
Interest payable	15,444,000	15,500,000			15,444,000
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Current borrowing capacity							$ 65,000,000
Remaining borrowing capacity	31,100,000				31,100,000
Domestic Line of Credit [Member]
Debt, Long-term and Short-term, Combined Amount [Abstract]
Revolving line of credit	$ 19,881,000	19,881,000			19,881,000
Line of Credit Facility [Abstract]
Additional Borrowings					0
Repayments					$ 0
Domestic Line of Credit [Member] | Base Rate [Member]
Line of Credit Facility [Abstract]
Rate	4.75%				4.75%
Foreign Line of Credit [Member]
Line of Credit Facility [Abstract]
Additional Borrowings					$ 0
Foreign Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on variable rate					2.50%
Foreign Line of Credit [Member] | Letter of Credit One [Member]
Debt, Long-term and Short-term, Combined Amount [Abstract]
Revolving line of credit	$ 12,000,000	$ 12,000,000			$ 12,000,000
Foreign Line of Credit [Member] | Letter of Credit One [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Rate	3.375%				3.375%
Foreign Line of Credit [Member] | Letter of Credit Two [Member]
Debt, Long-term and Short-term, Combined Amount [Abstract]
Revolving line of credit	$ 2,000,000				$ 2,000,000
Foreign Line of Credit [Member] | Letter of Credit Two [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Rate	3.375%				3.375%
US Facility [Member] | Base Rate [Member]
Line of Credit Facility [Abstract]
Basis spread on variable rate					1.50%