Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2013	Mar. 31, 2013
Accounts receivable - trade, allowance for doubtful accounts (in dollars)	$ 1,743	$ 1,760
PROPERTY, PLANT AND EQUIPMENT, accumulated depreciation (in dollars)	62,910	50,127
INTANGIBLE ASSETS, accumulated amortization (in dollars)	$ 55,453	$ 44,155
General partner, interest (as a percent)	0.10%	0.10%
General partner, notional units outstanding	53,676	53,676
Limited partners, interest (as a percent)	99.90%	99.90%
Common units
Units outstanding	47,703,313	47,703,313
Subordinated units
Units outstanding	5,919,346	5,919,346