Acquisitions (Acquisitions Narrative) (Details) $ in Thousands		6 Months Ended
		Sep. 30, 2015 USD ($) businesses_acquired		Sep. 30, 2014 USD ($) businesses_acquired
Business Acquisition [Line Items]
Goodwill, acquired during period	[1]	$ 45,537
Net cash paid for acquisitions		$ 98,144		$ 29,834
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Number of businesses acquired | businesses_acquired		12		8
Historical annual sales of acquired businesses		$ 80,000		$ 36,000
Business acquisition, transaction costs		1,900		1,000
Business combination, pro forma information, revenue of acquiree since acquisition date, actual		17,000		10,000
Fair value of trade receivables acquired		6,100
Gross contractual amounts of acquired receivables		6,700
Goodwill, acquired during period		45,400
Goodwill deductible for income tax purposes		41,000
Fair value of total consideration transferred				34,000
Net cash paid for acquisitions		98,144	[2]	30,000
Stock issued for acquisition				$ 4,000
Series of Individually Immaterial Business Acquisitions [Member] | Customer relationships [Member]
Business Acquisition [Line Items]
Other intangible assets acquired		28,000
Series of Individually Immaterial Business Acquisitions [Member] | Non-competition agreements [Member]
Business Acquisition [Line Items]
Other intangible assets acquired		7,100
Distribution Business Segment [Member]
Business Acquisition [Line Items]
Goodwill, acquired during period	[1]	23,732
Distribution Business Segment [Member] | Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Number of businesses acquired | businesses_acquired				8
Historical annual sales of acquired businesses				$ 36,000
Business acquisition, transaction costs				1,000
Business combination, pro forma information, revenue of acquiree since acquisition date, actual				10,000
Fair value of total consideration transferred				34,000
Net cash paid for acquisitions		$ 53,227	[2]	30,000
Stock issued for acquisition				$ 4,000

[1] Includes acquisitions completed during the current year and adjustments made to prior year acquisitions.

[2] 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.