Summary by Business Segment (Financial Information by Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Segment Reporting Information [Line Items]
Net Sales	$ 1,313,587		$ 1,279,891
Cost of products sold (excluding depreciation)	583,406		575,543
Selling, distribution and administrative expenses	494,713		473,475
Depreciation	72,635		67,030
Amortization	7,752		7,229
Total costs and expenses	1,158,506		1,123,277
Operating Income	155,081		156,614
Distribution Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	1,183,612		1,141,084
Cost of products sold (excluding depreciation)	520,933		505,127
Selling, distribution and administrative expenses	449,639		427,231
Depreciation	66,462		61,664
Amortization	6,724		6,062
Total costs and expenses	1,043,758		1,000,084
Operating Income	139,854		141,000
All Other Operations Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	137,043		147,270
Cost of products sold (excluding depreciation)	69,541		78,879
Selling, distribution and administrative expenses	45,074		43,540
Depreciation	6,173		5,366
Amortization	1,028		1,167
Total costs and expenses	121,816		128,952
Operating Income	15,227		18,318
Eliminations And Other Member
Segment Reporting Information [Line Items]
Net Sales	(7,068)	[1]	(8,463)	[1]
Cost of products sold (excluding depreciation)	(7,068)	[1]	(8,463)	[1]
Selling, distribution and administrative expenses	0		2,704
Depreciation	0		0
Amortization	0		0
Total costs and expenses	(7,068)		(5,759)
Operating Income	0		(2,704)
Gas and Rent [Member]
Segment Reporting Information [Line Items]
Net Sales	825,591		809,892
Gas and Rent [Member] | Distribution Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	696,565		672,486
Gas and Rent [Member] | All Other Operations Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	136,092		145,867
Gas and Rent [Member] | Eliminations And Other Member
Segment Reporting Information [Line Items]
Net Sales	(7,066)		(8,461)
Hardgoods [Member]
Segment Reporting Information [Line Items]
Net Sales	487,996		469,999
Hardgoods [Member] | Distribution Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	487,047		468,598
Hardgoods [Member] | All Other Operations Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	951		1,403
Hardgoods [Member] | Eliminations And Other Member
Segment Reporting Information [Line Items]
Net Sales	$ (2)		$ (2)

[1] Amounts in the “Eliminations and Other” column represent the elimination of intercompany sales and associated gross profit on sales from the Company’s All Other Operations business segment to its Distribution business segment.