Other Noncurrent Assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Mar. 31, 2013
Other noncurrent assets
Deposits	$ 4,340	[1]	$ 3,885	[1]
Deferred financing costs	21,851		16,080
Investment in affiliates	545		1,877
Capitalized software, net	3,129		3,993
Retirement plans	25,066		17,655
Other	10,269		7,559
Other noncurrent assets, total	$ 65,200		$ 51,049

[1] Deposits principally represent amounts held by beneficiaries as cash collateral for the Company’s contingent obligations with respect to certain environmental matters, workers' compensation insurance, and operating lease commitments.