Other Indebtedness - Schedule of Floating Rate Loan Stock, Notes Outstanding (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Amount	$ 56.3	$ 57.8
Floating Rate Loan Stock, U.S. Dollar, Start Year 2004 [Member]
Debt Instrument [Line Items]
Interest Rate	6.41%	6.72%
Amount	$ 6.5	$ 6.5
Floating Rate Loan Stock, U.S. Dollar, Start Year 2006 [Member]
Debt Instrument [Line Items]
Interest Rate	6.21%	6.52%
Amount	$ 10.0	$ 10.0
Floating Rate Loan Stock, U.S. Dollar [Member]
Debt Instrument [Line Items]
Amount	$ 16.5	$ 16.5
Floating Rate Loan Stock, Euro, Start Year 2005 [Member]
Debt Instrument [Line Items]
Interest Rate	3.58%	3.68%
Amount	$ 13.3	$ 13.8
Floating Rate Loan Stock, Euro, Start Year 2006 [Member]
Debt Instrument [Line Items]
Interest Rate	3.58%	3.68%
Amount	$ 11.6	$ 12.0
Floating Rate Loan Stock, Euro, Start Year 2007 [Member]
Debt Instrument [Line Items]
Interest Rate	3.47%	3.59%
Amount	$ 14.9	$ 15.5
Floating Rate Loan Stock, Euro [Member]
Debt Instrument [Line Items]
Amount	$ 39.8	$ 41.3
London Interbank Offered Rate (LIBOR) [Member] \| Floating Rate Loan Stock, U.S. Dollar, Start Year 2004 [Member]
Debt Instrument [Line Items]
Interest rate basis spread	4.20%	4.20%
London Interbank Offered Rate (LIBOR) [Member] \| Floating Rate Loan Stock, U.S. Dollar, Start Year 2006 [Member]
Debt Instrument [Line Items]
Interest rate basis spread	4.00%	4.00%
London Interbank Offered Rate (LIBOR) [Member] \| Floating Rate Loan Stock, Euro, Start Year 2005 [Member]
Debt Instrument [Line Items]
Interest rate basis spread	4.00%	4.00%
London Interbank Offered Rate (LIBOR) [Member] \| Floating Rate Loan Stock, Euro, Start Year 2006 [Member]
Debt Instrument [Line Items]
Interest rate basis spread	4.00%	4.00%
London Interbank Offered Rate (LIBOR) [Member] \| Floating Rate Loan Stock, Euro, Start Year 2007 [Member]
Debt Instrument [Line Items]
Interest rate basis spread	3.90%	3.90%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Carrying value as of the balance sheet date of notes payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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