Summary by Business Segment (Financial Information by Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Net Sales	$ 1,242,846		$ 1,207,708		$ 3,804,707		$ 3,694,574
Cost of products sold (excluding depreciation)	537,670		530,565		1,676,225		1,660,447
Selling, distribution and administrative expenses	472,687		459,175		1,420,617		1,368,776
Restructuring and other special charges (benefits), net	0		(1,729)		0		6,426
Depreciation	69,905		65,804		205,422		194,820
Amortization	7,665		6,614		22,141		19,950
Operating Income	154,919		147,279		480,302		444,155
Distribution Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	1,125,522		1,076,102		3,406,182		3,271,594
Cost of products sold (excluding depreciation)	484,083		465,030		1,480,870		1,453,426
Selling, distribution and administrative expenses	427,440		405,591		1,282,022		1,210,753
Restructuring and other special charges (benefits), net	0		0		0		0
Depreciation	63,968		60,372		188,497		178,759
Amortization	6,620		5,384		18,875		16,171
Operating Income	143,411		139,725		435,918		412,485
All Other Operations Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	124,663		139,670		422,243		449,355
Cost of products sold (excluding depreciation)	60,926		73,599		219,073		233,396
Selling, distribution and administrative expenses	43,409		44,866		132,361		130,749
Restructuring and other special charges (benefits), net	0		0		0		0
Depreciation	5,937		5,432		16,925		16,061
Amortization	1,045		1,230		3,266		3,779
Operating Income	13,346		14,543		50,618		65,370
Gas and Rent [Member]
Segment Reporting Information [Line Items]
Net Sales	790,895		772,974		2,423,573		2,332,093
Gas and Rent [Member] | Distribution Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	674,465		642,884		2,028,340		1,914,092
Gas and Rent [Member] | All Other Operations Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	123,768		138,152		418,948		444,371
Hardgoods [Member]
Segment Reporting Information [Line Items]
Net Sales	451,951		434,734		1,381,134		1,362,481
Hardgoods [Member] | Distribution Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	451,057		433,218		1,377,842		1,357,502
Hardgoods [Member] | All Other Operations Business Segment [Member]
Segment Reporting Information [Line Items]
Net Sales	895		1,518		3,295		4,984
Eliminations And Other Member
Segment Reporting Information [Line Items]
Net Sales	(7,339)	[1]	(8,064)	[1]	(23,718)	[1]	(26,375)	[1]
Cost of products sold (excluding depreciation)	(7,339)	[1]	(8,064)	[1]	(23,718)	[1]	(26,375)	[1]
Selling, distribution and administrative expenses	1,838		8,718		6,234		27,274
Restructuring and other special charges (benefits), net	0		(1,729)		0		6,426
Depreciation	0		0		0		0
Amortization	0		0		0		0
Operating Income	(1,838)		(6,989)		(6,234)		(33,700)
Eliminations And Other Member | Gas and Rent [Member]
Segment Reporting Information [Line Items]
Net Sales	(7,338)		(8,062)		(23,715)		(26,370)
Eliminations And Other Member | Hardgoods [Member]
Segment Reporting Information [Line Items]
Net Sales	$ (1)		$ (2)		$ (3)		$ (5)

[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.