Acquisitions (Summary of the Consideration Transferred and the Fair Values of the Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands		3 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015
Consideration
Cash		$ 26,182	$ 23,463
Recognized amounts of identifiable assets acquired and liabilities assumed
Goodwill		1,328,551		$ 1,313,644
Series of Individually Immaterial Business Acquisitions [Member]
Consideration
Cash	[1]	26,182
Recognized amounts of identifiable assets acquired and liabilities assumed
Current assets, net		4,409
Plant and equipment		3,523
Other intangible assets		11,840
Current liabilities		(4,255)
Non-current liabilities		(1,219)
Total identifiable net assets		14,298
Goodwill		11,884
Recognized amounts of identifiable assets acquired, goodwill, and liabilities assumed, net		26,182
Distribution Business Segment [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed
Goodwill		1,131,460		$ 1,116,569
Distribution Business Segment [Member] | Series of Individually Immaterial Business Acquisitions [Member]
Consideration
Cash	[1]	26,182
Recognized amounts of identifiable assets acquired and liabilities assumed
Current assets, net		4,409
Plant and equipment		3,523
Other intangible assets		11,840
Current liabilities		(4,255)
Non-current liabilities		(1,219)
Total identifiable net assets		14,298
Goodwill		11,884
Recognized amounts of identifiable assets acquired, goodwill, and liabilities assumed, net		$ 26,182

[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.