Inventories (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Inventories [Abstract]
Finished goods and work in process	$ 370.9	$ 325.4
Raw materials	453.6	372.7
Supplies and spare parts	194.0	197.1
Inventories at FIFO cost	1,018.5	895.2
LIFO reserve	(80.6)	(33.3)
Net inventories	$ 937.9	$ 861.9

Name:	rkt_InventoriesAbstract
Namespace Prefix:	rkt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Other Inventories, Supplies and Spare Parts

+ References

No definition available.

+ Details

Name:	rkt_OtherInventoriesSuppliesAndSpareParts
Namespace Prefix:	rkt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of FIFO (first in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6361739&loc=d3e7789-107766

+ Details

Name:	us-gaap_FIFOInventoryAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before valuation reserves of merchandise or goods held by the entity that are readily available for sale and items held by the entity which are partially complete or in the process of being readied for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(1),(3))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryFinishedGoodsAndWorkInProcess
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of difference between inventory at lower of LIFO cost or market and inventory at lower of other inventory accounting method cost or market, for example, but not limited to, FIFO or average cost.

+ References

+ Details

Name:	us-gaap_InventoryLIFOReserve
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

+ Details

Name:	us-gaap_InventoryNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(4))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryRawMaterials
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant