Commitments and Contingencies (Details ) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Asset retirement obligations
Asset retirement obligations	$ 2,700,000		$ 2,700,000
Future minimum lease payments
2015 (six months)	71,007,000		71,007,000
2016	106,384,000		106,384,000
2017	88,666,000		88,666,000
2018	74,265,000		74,265,000
2019	49,907,000		49,907,000
Thereafter	117,125,000		117,125,000
Total	507,354,000		507,354,000
Rental expense	$ 29,300,000	$ 23,600,000	$ 54,600,000	$ 45,500,000