Investment income - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013
Restructuring Cost and Reserve [Line Items]
Realized gains from sale of debt and equity investments available-for-sale	$ 1.1	$ 2.5
Realized gain on sale of title plant	0.8
Non cash charge on early retirement of convertible senior notes		5.4
Loss on sale of equity investment		1.5
Gain on non-title-related insurance policy proceeds		1.7
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Non-cash charge related to office closures	$ 1.1

The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a)

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Includes, but is not limited to, one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, and relocating employees, and termination benefits associated with an ongoing benefit arrangement. Excludes expenses associated with special or contractual termination benefits, a discontinued operation or an asset retirement obligation.

+ References

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

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section P

-Subsection 3, 4

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

+ References

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

-Publisher FASB

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The difference between the carrying value and the sale price of equity securities, not separately or otherwise categorized as trading or available-for-sale. This element includes investments in which the entity holds a small ownership stake (generally, less than 20% of the shares outstanding) and cannot exert significant influence.

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The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities.

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Consideration given by issuer of convertible debt to provide an incentive for debt holders to convert the debt to equity securities. The expense is equal to the fair value of all securities and other consideration transferred in the transaction in excess of the fair value of securities issuable pursuant to the original conversion terms.

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