Employee Benefit Arrangements - Defined Contribution Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
Jun. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Compensation And Retirement Disclosure [Abstract]
Company match percentage of participant's eligible compensation	6.00%	6.00%
Award vesting period	4 years	4 years
Cost recognized for defined contribution pension plans		$ 34.4	$ 38.2	$ 37.7

The amount of the cost recognized during the period for defined contribution plans.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration