Indebtedness (Narrative) (Details) | Jun. 29, 2018USD ($) | Aug. 09, 2017USD ($) | May 09, 2016USD ($) | Mar. 31, 2018USD ($) | Mar. 31, 2017USD ($) | Mar. 31, 2016USD ($) |
Line of Credit Facility [Line Items] | | | | | | |
Long-term debt | | | | $ 477,000 | $ 88,782,000 | |
Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Maximum borrowing capacity | | | $ 200,000,000 | | | |
Maximum amount outstanding | | | | 171,237,000 | 150,075,000 | $ 183,050,000 |
Weighted-average amount outstanding | | | | $ 142,001,000 | $ 127,727,000 | $ 158,256,000 |
Weighted-average interest rate | | | | 4.00% | 2.60% | 2.00% |
Unused commitments | | | | $ 0 | | |
Revolving credit agreement | Variable component | Minimum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | | 0.00% | | | |
Revolving credit agreement | Variable component | Maximum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | | 1.00% | | | |
Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, percentage of voting interests required to be pledged | | 65.00% | | | | |
Debt instrument, percentage of non-voting interests required to be pledged | | 100.00% | | | | |
Maximum borrowing capacity | | $ 170,000,000 | | | | |
Letter of credit | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Amount outstanding | | | | 9,825,000 | | |
London Interbank Offered Rate (LIBOR) | Revolving credit agreement | Variable component | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | | 1.00% | | | |
London Interbank Offered Rate (LIBOR) | Revolving credit agreement | Variable component | Minimum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | | 1.00% | | | |
London Interbank Offered Rate (LIBOR) | Revolving credit agreement | Variable component | Maximum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | | 2.00% | | | |
Federal Funds Effective Swap Rate | Revolving credit agreement | Variable component | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | | 0.50% | | | |
Letter of credit | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Maximum borrowing capacity | | | $ 25,000,000 | | | |
Swing-line loans | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Maximum borrowing capacity | | | $ 15,000,000 | | | |
Term Loan | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Long-term debt | | 50,000,000 | | | | |
Maximum borrowing capacity | | $ 50,000,000 | | | | |
Term Loan | Amended credit agreement | Minimum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, percentage of excess cash flow required as a prepayment | | 75.00% | | | | |
Term Loan | Amended credit agreement | Maximum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, percentage of excess cash flow required as a prepayment | | 50.00% | | | | |
Line of credit | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Maximum borrowing capacity | | $ 120,000,000 | | | | |
Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Long-term debt | | | | 0 | $ 88,400,000 | |
Revolving credit agreement | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Long-term debt | | 52,528,000 | | | | |
Unsecured debt | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Long-term debt | | | | 1,814,000 | 3,387,000 | |
Other liabilities (current) | Unsecured debt | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Long-term debt | | | | $ 1,596,000 | $ 3,169,000 | |
Debt Instrument, Redemption, Period Seven | Term Loan | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Amortization of debt issuance costs | | 1,250,000 | | | | |
Debt Instrument, Redemption, Period Eight | Term Loan | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Amortization of debt issuance costs | | $ 2,500,000 | | | | |
Debt Instrument, Redemption, Period One | Term Loan | Federal Funds Effective Swap Rate | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 0.50% | | | | |
Debt Instrument, Redemption, Period One | Line of credit | Base Rate | Amended credit agreement | Minimum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 0.25% | | | | |
Debt Instrument, Redemption, Period One | Line of credit | Base Rate | Amended credit agreement | Maximum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 2.00% | | | | |
Debt Instrument, Redemption, Period Two | Term Loan | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 2.50% | | | | |
Debt Instrument, Redemption, Period Two | Term Loan | London Interbank Offered Rate (LIBOR) | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 1.00% | | | | |
Debt Instrument, Redemption, Period Two | Line of credit | London Interbank Offered Rate (LIBOR) | Amended credit agreement | Minimum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 1.25% | | | | |
Debt Instrument, Redemption, Period Two | Line of credit | London Interbank Offered Rate (LIBOR) | Amended credit agreement | Maximum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 3.00% | | | | |
Debt Instrument, Redemption, Period Three | Term Loan | London Interbank Offered Rate (LIBOR) | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 3.50% | | | | |
Debt Instrument, Redemption, Period Four | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, covenant, fixed charge coverage ratio | | 1 | | | | |
Consolidated leverage ratio | | 4 | | | | |
Debt Instrument, Redemption, Period Five | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Consolidated leverage ratio | | 3 | | | | |
Debt Instrument, Redemption, Period Six | Amended credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, covenant, fixed charge coverage ratio | | 1.10 | | | | |
Second amended credit agreement | Letter of credit | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Maximum borrowing capacity | $ 10,000,000 | | | | | |
Second amended credit agreement | Term Loan | London Interbank Offered Rate (LIBOR) | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | 10.00% | | | | | |
Second amended credit agreement | Line of credit | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Maximum borrowing capacity | $ 10,000,000 | | | | | |
Second amended credit agreement | Debt Instrument, Redemption, Period One | Term Loan | Federal Funds Effective Swap Rate | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 0.50% | | | | |
Second amended credit agreement | Debt Instrument, Redemption, Period One | Line of credit | Base Rate | Revolving credit agreement | Minimum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 0.25% | | | | |
Second amended credit agreement | Debt Instrument, Redemption, Period One | Line of credit | Base Rate | Revolving credit agreement | Maximum | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 2.00% | | | | |
Second amended credit agreement | Debt Instrument, Redemption, Period Two | Term Loan | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 2.50% | | | | |
Second amended credit agreement | Debt Instrument, Redemption, Period Two | Term Loan | London Interbank Offered Rate (LIBOR) | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Basis spread on variable rate | | 1.00% | | | | |
June 2018 | Second amended credit agreement | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, covenant, minimum consolidated EBITDA | 3,000,000 | | | | | |
July 2018 | Second amended credit agreement | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, covenant, minimum consolidated EBITDA | 3,000,000 | | | | | |
August 2018 | Second amended credit agreement | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, covenant, minimum consolidated EBITDA | 3,000,000 | | | | | |
September 2018 and thereafter | Second amended credit agreement | Revolving credit agreement | | | | | | |
Line of Credit Facility [Line Items] | | | | | | |
Debt instrument, covenant, minimum consolidated EBITDA | $ 3,500,000 | | | | | |