SELECTED CONSOLIDATING FINANCIAL STATEMENTS OF PARENT, GUARANTORS AND NON-GUARANTORS (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidating Financial Statements, Captions
Net sales		$ 938,181		$ 790,528	$ 1,825,869	$ 1,635,591
Operating costs and expenses:
Cost of sales		703,654		591,206	1,354,931	1,239,997
Selling, general and administrative		56,193		60,256	118,152	121,221
Depreciation and amortization		31,998		29,466	63,813	58,933
Acquisition and integration expenses		1,432		1,144	1,977	1,604
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period	2,000	1,957	1,150		3,107
Total operating costs and expenses		795,234		682,072	1,541,980	1,421,755
Operating income (loss)		142,947		108,456	283,889	213,836
Intercompany interest and charges		0		0	0	0
Interest expense and other		16,668		17,671	33,900	44,133
Income (loss) from continuing operations, before income taxes		126,279		90,785	249,989	169,703
Income tax expense (benefit)		46,088		32,221	93,466	60,235
Income (loss) from continuing operations		80,191		58,564	156,523	109,468
Loss on discontinued operations, net		0		(76)	0	(765)
Net income		80,191		58,488	156,523	108,703
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		4,347		(7,575)	(11)	(6,034)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		84,538		50,913	156,512	102,669
Parent
Consolidating Financial Statements, Captions
Net sales		0		0	0	0
Operating costs and expenses:
Cost of sales		0		0	0	0
Selling, general and administrative		10,189		9,402	20,775	18,040
Depreciation and amortization		610		413	1,209	847
Acquisition and integration expenses		0		1,144	295	1,604
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period		1,957			3,107
Total operating costs and expenses		12,756		10,959	25,386	20,491
Operating income (loss)		(12,756)		(10,959)	(25,386)	(20,491)
Intercompany interest and charges		(49,217)		(46,440)	(98,554)	(98,184)
Interest expense and other		15,143		17,225	30,642	43,564
Income (loss) from continuing operations, before income taxes		21,318		18,256	42,526	34,129
Income tax expense (benefit)		8,709		6,588	18,889	11,820
Income (loss) from continuing operations		12,609		11,668		22,309
Loss on discontinued operations, net				0		0
Net income				11,668	23,637	22,309
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		0		0	0	232
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		12,609		11,668	23,637	22,541
Guarantors Subsidiaries
Consolidating Financial Statements, Captions
Net sales		914,943		766,759	1,777,419	1,586,904
Operating costs and expenses:
Cost of sales		687,053		572,740	1,321,190	1,201,781
Selling, general and administrative		41,412		46,617	87,585	94,647
Depreciation and amortization		30,282		27,779	60,415	55,445
Acquisition and integration expenses		1,432		0	1,682	0
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period		0			0
Total operating costs and expenses		760,179		647,136	1,470,872	1,351,873
Operating income (loss)		154,764		119,623	306,547	235,031
Intercompany interest and charges		48,441		45,636	96,952	96,228
Interest expense and other		2,062		2,183	4,493	2,645
Income (loss) from continuing operations, before income taxes		104,261		71,804	205,102	136,158
Income tax expense (benefit)		37,140		25,535	73,984	48,539
Income (loss) from continuing operations		67,121		46,269		87,619
Loss on discontinued operations, net				(76)		(765)
Net income				46,193	131,118	86,854
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		254		(698)	318	(1,396)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		67,375		45,495	131,436	85,458
Non-Guarantor Subsidiaries
Consolidating Financial Statements, Captions
Net sales		24,274		25,105	51,175	53,045
Operating costs and expenses:
Cost of sales		17,637		19,802	36,466	42,574
Selling, general and administrative		4,592		4,237	9,792	8,534
Depreciation and amortization		1,106		1,274	2,189	2,641
Acquisition and integration expenses		0		0	0	0
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period		0			0
Total operating costs and expenses		23,335		25,313	48,447	53,749
Operating income (loss)		939		(208)	2,728	(704)
Intercompany interest and charges		776		804	1,602	1,956
Interest expense and other		(537)		(1,737)	(1,235)	(2,076)
Income (loss) from continuing operations, before income taxes		700		725	2,361	(584)
Income tax expense (benefit)		239		98	593	(124)
Income (loss) from continuing operations		461		627		(460)
Loss on discontinued operations, net				0		0
Net income				627	1,768	(460)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		4,093		(6,877)	(329)	(4,870)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		4,554		(6,250)	1,439	(5,330)
Eliminations
Consolidating Financial Statements, Captions
Net sales		(1,036)		(1,336)	(2,725)	(4,358)
Operating costs and expenses:
Cost of sales		(1,036)		(1,336)	(2,725)	(4,358)
Selling, general and administrative		0		0	0	0
Depreciation and amortization		0		0		0
Acquisition and integration expenses		0		0	0	0
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period		0			0
Total operating costs and expenses		(1,036)		(1,336)	(2,725)	(4,358)
Operating income (loss)		0		0	0	0
Intercompany interest and charges		0		0	0	0
Interest expense and other		0		0	0	0
Income (loss) from continuing operations, before income taxes		0		0	0	0
Income tax expense (benefit)		0		0	0	0
Income (loss) from continuing operations		0		0		0
Loss on discontinued operations, net				0		0
Net income				0	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		0		0	0	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		$ 0		$ 0	$ 0	$ 0