LONG-TERM DEBT: (Details) (USD $)	6 Months Ended			6 Months Ended		6 Months Ended			6 Months Ended			6 Months Ended					6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2014	Sep. 30, 2014 Interest rate swap Derivative Agreement 20140310 [Member] Cash flow hedge	Mar. 10, 2014 Interest rate swap Derivative Agreement 20140310 [Member] Cash flow hedge	Sep. 30, 2014 LIBOR Interest rate swap Derivative Agreement 20140310 [Member]	Sep. 30, 2014 Term loan credit agreement	Mar. 31, 2014 Term loan credit agreement	Sep. 30, 2014 Term loan credit agreement Quarterly installments payable through September 2017	Sep. 30, 2014 Term loan credit agreement Quarterly installments payable through June 2018	Sep. 30, 2014 Term loan credit agreement Final payment due on October 9, 2018	Sep. 30, 2014 Term loan credit agreement LIBOR	Sep. 30, 2014 Capital leases and installment payment obligations	Mar. 31, 2014 Capital leases and installment payment obligations	Sep. 30, 2014 Other debt and long-term liabilities	Mar. 31, 2014 Other debt and long-term liabilities	Sep. 30, 2014 Revolving credit facility	Sep. 30, 2014 Revolving credit facility LIBOR
Long-term debt
Total long-term debt and capital leases	$ 304,987,000		$ 317,610,000				$ 285,000,000	$ 292,500,000					$ 8,905,000	$ 12,990,000	$ 11,082,000	$ 12,120,000
Less current installments	34,118,000		28,567,000
Long-term debt, excluding current installments	270,869,000		289,043,000
Long-term debt stated interest rate percentage, minimum													4.00%
Long-term debt stated interest rate percentage, maximum													8.00%
Maximum remaining maturity period of debt													8 years
Existing debt repaid with proceeds of term loan	10,858,000	9,233,000
Aggregate amount of borrowing commitment							300,000,000										300,000,000
Required quarterly installment payments									7,500,000	11,300,000
Final payment of long-term debt											161,300,000
Long-term debt variable interest rate description						LIBOR
Long-term debt basis spread on variable interest rate (as a percent)												2.00%						2.00%
Weighted-average interest rate on long-term debt (as a percent)	2.30%
Outstanding revolving credit borrowings																	0
Outstanding letters of credit	2,200,000
Revolving credit facility dividend restrictions amount, maximum																	30,000,000
Fixed interest rate payable on swap (as a percent)					0.98%
Notional amount of derivative					50,000,000
LIBOR rate (as a percent)	0.23%
Fair market value of the derivative				0
Unrealized loss of the derivative recorded in other comprehensive income (loss)				$ 100,000