Commitments and Contingencies - (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012 D	Sep. 30, 2011	Sep. 30, 2012 D	Sep. 30, 2011
Commitments and Contingencies Disclosure [Abstract]
Rental expense under leases	$ 5.0	$ 5.2	$ 15.1	$ 15.4
Rental income	$ 0	$ 0.3	$ 0.5	$ 0.9
Number days required to repurchase mortgage loans	90		90

Income earned by providing the use of assets to an outside party in exchange for a payment or series of payments that is nonoperating in nature.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Name:	us-gaap_RentalIncomeNonoperating
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration