XML 197 R66.htm IDEA: XBRL DOCUMENT v2.4.0.8
Investments - Risk Exposure on Mortgage Backed Securities (Detail)
Jun. 30, 2013
Dec. 31, 2012
Dec. 31, 2011
Subprime mortgage-backed securities
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Subprime mortgage-backed securities | Vintage Year 2007
      
Concentration Risk [Line Items]      
Credit exposure 28.70% 29.10% 26.90%
Subprime mortgage-backed securities | Vintage Year 2006
      
Concentration Risk [Line Items]      
Credit exposure 32.70% 36.80% 41.20%
Subprime mortgage-backed securities | Vintage Year 2005 and prior
      
Concentration Risk [Line Items]      
Credit exposure 38.60% 34.10% 31.90%
Subprime mortgage-backed securities | Acceptable Rating Organizations
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Subprime mortgage-backed securities | Acceptable Rating Organizations | AAA Rating
      
Concentration Risk [Line Items]      
Credit exposure 0.40% 1.10% 2.90%
Subprime mortgage-backed securities | Acceptable Rating Organizations | AA Rating
      
Concentration Risk [Line Items]      
Credit exposure 1.10% 1.00% 1.20%
Subprime mortgage-backed securities | Acceptable Rating Organizations | A Rating
      
Concentration Risk [Line Items]      
Credit exposure 5.40% 5.40% 4.50%
Subprime mortgage-backed securities | Acceptable Rating Organizations | BBB Rating
      
Concentration Risk [Line Items]      
Credit exposure 6.00% 6.00% 8.80%
Subprime mortgage-backed securities | Acceptable Rating Organizations | BB and Below Rating
      
Concentration Risk [Line Items]      
Credit exposure 87.10% 86.50% 82.60%
Subprime mortgage-backed securities | NAIC Designation
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Subprime mortgage-backed securities | NAIC Designation | NAIC Designation of 1
      
Concentration Risk [Line Items]      
Credit exposure 58.30% 60.30% 78.10%
Subprime mortgage-backed securities | NAIC Designation | NAIC Designation of 2
      
Concentration Risk [Line Items]      
Credit exposure 8.30% 11.90% 4.70%
Subprime mortgage-backed securities | NAIC Designation | NAIC Designation of 3
      
Concentration Risk [Line Items]      
Credit exposure 22.70% 16.70% 13.40%
Subprime mortgage-backed securities | NAIC Designation | NAIC Designation of 4
      
Concentration Risk [Line Items]      
Credit exposure 9.50% 8.10% 2.70%
Subprime mortgage-backed securities | NAIC Designation | NAIC Designation of 5
      
Concentration Risk [Line Items]      
Credit exposure 1.00% 2.80% 0.50%
Subprime mortgage-backed securities | NAIC Designation | NAIC Designation of 6
      
Concentration Risk [Line Items]      
Credit exposure 0.20% 0.20% 0.60%
Alt-A residential mortgage-backed securities
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Alt-A residential mortgage-backed securities | Vintage Year 2007
      
Concentration Risk [Line Items]      
Credit exposure 21.10% 20.40% 18.80%
Alt-A residential mortgage-backed securities | Vintage Year 2006
      
Concentration Risk [Line Items]      
Credit exposure 25.90% 25.90% 25.30%
Alt-A residential mortgage-backed securities | Vintage Year 2005 and prior
      
Concentration Risk [Line Items]      
Credit exposure 53.00% 53.70% 55.90%
Alt-A residential mortgage-backed securities | Acceptable Rating Organizations
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Alt-A residential mortgage-backed securities | Acceptable Rating Organizations | AAA Rating
      
Concentration Risk [Line Items]      
Credit exposure 0.10% 0.20% 1.00%
Alt-A residential mortgage-backed securities | Acceptable Rating Organizations | AA Rating
      
Concentration Risk [Line Items]      
Credit exposure 0.30% 1.20% 2.30%
Alt-A residential mortgage-backed securities | Acceptable Rating Organizations | A Rating
      
Concentration Risk [Line Items]      
Credit exposure 1.80% 1.50% 7.50%
Alt-A residential mortgage-backed securities | Acceptable Rating Organizations | BBB Rating
      
Concentration Risk [Line Items]      
Credit exposure 3.70% 4.10% 3.90%
Alt-A residential mortgage-backed securities | Acceptable Rating Organizations | BB and Below Rating
      
Concentration Risk [Line Items]      
Credit exposure 94.10% 93.00% 85.30%
Alt-A residential mortgage-backed securities | NAIC Designation
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Alt-A residential mortgage-backed securities | NAIC Designation | NAIC Designation of 1
      
Concentration Risk [Line Items]      
Credit exposure 43.60% 34.10% 38.70%
Alt-A residential mortgage-backed securities | NAIC Designation | NAIC Designation of 2
      
Concentration Risk [Line Items]      
Credit exposure 12.90% 11.90% 11.00%
Alt-A residential mortgage-backed securities | NAIC Designation | NAIC Designation of 3
      
Concentration Risk [Line Items]      
Credit exposure 24.40% 18.80% 16.40%
Alt-A residential mortgage-backed securities | NAIC Designation | NAIC Designation of 4
      
Concentration Risk [Line Items]      
Credit exposure 15.60% 26.90% 24.00%
Alt-A residential mortgage-backed securities | NAIC Designation | NAIC Designation of 5
      
Concentration Risk [Line Items]      
Credit exposure 2.80% 7.50% 9.00%
Alt-A residential mortgage-backed securities | NAIC Designation | NAIC Designation of 6
      
Concentration Risk [Line Items]      
Credit exposure 0.70% 0.80% 0.90%
Commercial mortgage-backed securities
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Commercial mortgage-backed securities | Vintage Year 2007
      
Concentration Risk [Line Items]      
Credit exposure 37.00% 37.40% 33.40%
Commercial mortgage-backed securities | Vintage Year 2006
      
Concentration Risk [Line Items]      
Credit exposure 31.40% 30.20% 26.50%
Commercial mortgage-backed securities | Vintage Year 2005 and prior
      
Concentration Risk [Line Items]      
Credit exposure 31.40% 32.10% 39.80%
Commercial mortgage-backed securities | Vintage Year 2008
      
Concentration Risk [Line Items]      
Credit exposure 0.20% 0.30% 0.30%
Commercial mortgage-backed securities | Acceptable Rating Organizations
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Commercial mortgage-backed securities | Acceptable Rating Organizations | AAA Rating
      
Concentration Risk [Line Items]      
Credit exposure 37.30% 38.10% 47.30%
Commercial mortgage-backed securities | Acceptable Rating Organizations | AA Rating
      
Concentration Risk [Line Items]      
Credit exposure 18.40% 17.20% 10.10%
Commercial mortgage-backed securities | Acceptable Rating Organizations | A Rating
      
Concentration Risk [Line Items]      
Credit exposure 11.10% 11.20% 16.50%
Commercial mortgage-backed securities | Acceptable Rating Organizations | BBB Rating
      
Concentration Risk [Line Items]      
Credit exposure 18.10% 17.80% 13.50%
Commercial mortgage-backed securities | Acceptable Rating Organizations | BB and Below Rating
      
Concentration Risk [Line Items]      
Credit exposure 15.10% 15.70% 12.60%
Commercial mortgage-backed securities | NAIC Designation
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Commercial mortgage-backed securities | NAIC Designation | NAIC Designation of 1
      
Concentration Risk [Line Items]      
Credit exposure 98.70% 98.30% 92.70%
Commercial mortgage-backed securities | NAIC Designation | NAIC Designation of 2
      
Concentration Risk [Line Items]      
Credit exposure 0.90% 1.40% 2.60%
Commercial mortgage-backed securities | NAIC Designation | NAIC Designation of 3
      
Concentration Risk [Line Items]      
Credit exposure 0.30% 0.20% 3.60%
Commercial mortgage-backed securities | NAIC Designation | NAIC Designation of 4
      
Concentration Risk [Line Items]      
Credit exposure 0.10% 0.10% 0.70%
Commercial mortgage-backed securities | NAIC Designation | NAIC Designation of 6
      
Concentration Risk [Line Items]      
Credit exposure     0.40%
Other asset-backed securities
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Other asset-backed securities | Vintage Year 2007
      
Concentration Risk [Line Items]      
Credit exposure 47.70% 18.40% 24.80%
Other asset-backed securities | Vintage Year 2006
      
Concentration Risk [Line Items]      
Credit exposure   9.50% 9.50%
Other asset-backed securities | Vintage Year 2005 and prior
      
Concentration Risk [Line Items]      
Credit exposure   18.80% 24.70%
Other asset-backed securities | Vintage Year 2008
      
Concentration Risk [Line Items]      
Credit exposure 5.00% 5.90% 7.00%
Other asset-backed securities | Vintage Year 2012
      
Concentration Risk [Line Items]      
Credit exposure 23.50% 24.60%  
Other asset-backed securities | Vintage Year 2011
      
Concentration Risk [Line Items]      
Credit exposure 12.60% 14.90% 18.00%
Other asset-backed securities | Vintage Year 2010
      
Concentration Risk [Line Items]      
Credit exposure 5.40% 5.80% 9.60%
Other asset-backed securities | Vintage Year 2009
      
Concentration Risk [Line Items]      
Credit exposure 2.20% 2.10% 6.40%
Other asset-backed securities | Vintage Year 2006 and prior
      
Concentration Risk [Line Items]      
Credit exposure   28.30%  
Other asset-backed securities | Vintage Year 2013
      
Concentration Risk [Line Items]      
Credit exposure 3.60%    
Other asset-backed securities | Acceptable Rating Organizations
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Other asset-backed securities | Acceptable Rating Organizations | AAA Rating
      
Concentration Risk [Line Items]      
Credit exposure 92.70% 91.90% 86.60%
Other asset-backed securities | Acceptable Rating Organizations | AA Rating
      
Concentration Risk [Line Items]      
Credit exposure 2.10% 0.90% 3.10%
Other asset-backed securities | Acceptable Rating Organizations | A Rating
      
Concentration Risk [Line Items]      
Credit exposure 3.60% 4.90% 4.90%
Other asset-backed securities | Acceptable Rating Organizations | BBB Rating
      
Concentration Risk [Line Items]      
Credit exposure 0.90% 1.70% 3.80%
Other asset-backed securities | Acceptable Rating Organizations | BB and Below Rating
      
Concentration Risk [Line Items]      
Credit exposure 0.70% 0.60% 1.60%
Other asset-backed securities | NAIC Designation
      
Concentration Risk [Line Items]      
Credit exposure 100.00% 100.00% 100.00%
Other asset-backed securities | NAIC Designation | NAIC Designation of 1
      
Concentration Risk [Line Items]      
Credit exposure 98.40% 97.70% 96.10%
Other asset-backed securities | NAIC Designation | NAIC Designation of 2
      
Concentration Risk [Line Items]      
Credit exposure 0.90% 1.70% 2.30%
Other asset-backed securities | NAIC Designation | NAIC Designation of 3
      
Concentration Risk [Line Items]      
Credit exposure 0.00% 0.10% 0.00%
Other asset-backed securities | NAIC Designation | NAIC Designation of 4
      
Concentration Risk [Line Items]      
Credit exposure 0.00% 0.00% 0.20%
Other asset-backed securities | NAIC Designation | NAIC Designation of 5
      
Concentration Risk [Line Items]      
Credit exposure 0.00% 0.00% 1.40%
Other asset-backed securities | NAIC Designation | NAIC Designation of 6
      
Concentration Risk [Line Items]      
Credit exposure 0.70% 0.50% 0.00%