Retirement and Other Postretirement Benefit Plans (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Fair value of pension assets
Fair value measurements	$ 110.8
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	110.8
Actual allocations of Plan assets (as a percent)	100.00%	100.00%
Target allocations by asset class (as a percent)	100.00%	100.00%
Equity funds
Fair value of pension assets
Fair value measurements	59.7
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	59.7
U.K. Equity Fund
Reconciliation of Level 3 Assets
Actual allocations of Plan assets (as a percent)	27.80%	29.90%
Target allocations by asset class (as a percent)	31.00%	30.40%
Total invested in equities (as a percent)	50.00%
Overseas Equity Fund
Reconciliation of Level 3 Assets
Actual allocations of Plan assets (as a percent)	26.10%	30.70%
Target allocations by asset class (as a percent)	31.00%	30.40%
Total invested in equities (as a percent)	50.00%
Active Corporate Bond Funds
Fair value of pension assets
Fair value measurements	45.6
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	45.6
Actual allocations of Plan assets (as a percent)	41.10%	34.30%
Target allocations by asset class (as a percent)	32.90%	34.10%
Diversified Investment Funds
Fair value of pension assets
Fair value measurements	2.9
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	2.9
Actual allocations of Plan assets (as a percent)	2.60%	2.60%
Target allocations by asset class (as a percent)	2.50%	2.60%
Insurance Contracts
Fair value of pension assets
Fair value measurements	2.6
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	2.6
Actual allocations of Plan assets (as a percent)	2.40%	2.50%
Target allocations by asset class (as a percent)	2.60%	2.50%
Level 2
Fair value of pension assets
Fair value measurements	105.7
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	105.7
Level 2 \| Equity funds
Fair value of pension assets
Fair value measurements	59.7
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	59.7
Level 2 \| Active Corporate Bond Funds
Fair value of pension assets
Fair value measurements	45.6
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	45.6
Level 2 \| Diversified Investment Funds
Fair value of pension assets
Fair value measurements	0.4
Reconciliation of Level 3 Assets
Fair value of plan assets - end of year	0.4
Level 3
Fair value of pension assets
Fair value measurements	5.1
Reconciliation of Level 3 Assets
Fair value of plan assets - beginning of year	5.5
Actual return on plan assets	0.1
Purchases, sales and settlements	(0.4)
Changes due to exchange rates	(0.1)
Fair value of plan assets - end of year	5.1
Level 3 \| Diversified Investment Funds
Fair value of pension assets
Fair value measurements	2.5
Reconciliation of Level 3 Assets
Fair value of plan assets - beginning of year	2.8
Purchases, sales and settlements	(0.3)
Fair value of plan assets - end of year	2.5
Level 3 \| Insurance Contracts
Fair value of pension assets
Fair value measurements	2.6
Reconciliation of Level 3 Assets
Fair value of plan assets - beginning of year	2.7
Actual return on plan assets	0.1
Purchases, sales and settlements	(0.1)
Changes due to exchange rates	(0.1)
Fair value of plan assets - end of year	$ 2.6

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Actual Return on Plan Assets (Component of Net Periodic Pension Cost)

-URI http://asc.fasb.org/extlink&oid=6504226

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost)

-URI http://asc.fasb.org/extlink&oid=6504192

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 106

-Paragraph 518

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 87

-Paragraph 264

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(iv)(b)(i)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References+ Details