Supplemental Cash Flow Information (Noncash Investing and Financing Activities) (Details) - USD ($) $ in Thousands		6 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Noncash or Part Noncash Acquisitions [Line Items]
Net cash paid for acquisitions		$ (98,144)	$ (29,834)
Series of Individually Immaterial Business Acquisitions [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Fair value of assets acquired		115,105	46,048
Net cash paid for acquisitions	[1]	(98,144)	(29,834)
Stock issued for acquisition	[2]	0	(4,458)
Liabilities assumed		$ 16,961	$ 11,756

[1] Includes cash paid, net of cash acquired, for current year acquisitions as well as payments for the settlement of holdback liabilities associated with prior year acquisitions.

[2] Represents shares of Airgas, Inc. common stock issued in connection with a single prior year acquisition.