FAIR VALUE (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012
Book value [Member]
Book value of debt [Abstract]
Long-term debt, book value	$ 353,600	$ 279,250
Book value [Member] | Senior notes payable [Member]
Book value of debt [Abstract]
Long-term debt, book value	353,600	229,250
Book value [Member] | Junior subordinated notes payable [Member]
Book value of debt [Abstract]
Long-term debt, book value	0	50,000
Estimated fair value [Member]
Estimated fair value of debt [Abstract]
Long-term debt, estimated fair value	353,600	279,250
Estimated fair value [Member] | Senior notes payable [Member]
Estimated fair value of debt [Abstract]
Long-term debt, estimated fair value	353,600	229,250
Estimated fair value [Member] | Junior subordinated notes payable [Member]
Estimated fair value of debt [Abstract]
Long-term debt, estimated fair value	$ 0	$ 50,000