Deferred Method of Accounting for Major Overhaul (Details) (Engine and Transmission Overhaul [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Engine and Transmission Overhaul [Member]
Capitalized and amortized:
Net amount of (gains) losses netted against depreciation expense	$ (74.6)	$ (33.6)	$ (22.5)

Amount of gain (loss) on sale or disposal of assets utilized in financial service operations.

No definition available.

Name:	us-gaap_GainsLossesOnSalesOfAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration