Acquisitions and Divestitures (Summary of Fair Values of the Assets Acquired and Liabilities Assumed) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Mar. 31, 2013
Business Acquisition [Line Items]
Goodwill	$ 1,277,266	$ 1,195,613
Distribution Business Segment [Member]
Business Acquisition [Line Items]
Goodwill	1,080,051	998,128
All Other Operations Business Segment [Member]
Business Acquisition [Line Items]
Goodwill	197,215	197,485
FY14 and FY13 Acquisitions [Member]
Business Acquisition [Line Items]
Current assets, net	12,494
Plant and equipment	40,503
Goodwill	82,153
Other intangible assets	56,439
Current liabilities	(7,340)
Non-current liabilities	(3,118)
Net assets acquired	181,131
FY14 and FY13 Acquisitions [Member] | Distribution Business Segment [Member]
Business Acquisition [Line Items]
Current assets, net	12,485
Plant and equipment	41,249
Goodwill	82,369
Other intangible assets	56,439
Current liabilities	(8,707)
Non-current liabilities	(3,118)
Net assets acquired	180,717
FY14 and FY13 Acquisitions [Member] | All Other Operations Business Segment [Member]
Business Acquisition [Line Items]
Current assets, net	9
Plant and equipment	(746)
Goodwill	(216)
Other intangible assets	0
Current liabilities	1,367
Non-current liabilities	0
Net assets acquired	$ 414