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Mortgage Loans by Property Type and Geographic Region (Detail) - USD ($) $ in Millions | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 2,200.8 | $ 2,213.2
Percent of Total | 100.00% | 100.00%
New England |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 55.2 | $ 56.1
Percent of Total | 2.50% | 2.50%
Middle Atlantic |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 154.5 | $ 155.5
Percent of Total | 7.00% | 7.00%
East North Central |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 291.3 | $ 282.0
Percent of Total | 13.20% | 12.80%
West North Central |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 208.4 | $ 210.1
Percent of Total | 9.50% | 9.50%
South Atlantic |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 481.7 | $ 494.4
Percent of Total | 21.90% | 22.30%
East South Central |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 88.1 | $ 88.8
Percent of Total | 4.00% | 4.00%
West South Central |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 245.4 | $ 247.4
Percent of Total | 11.20% | 11.20%
Mountain |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 254.9 | $ 251.2
Percent of Total | 11.60% | 11.40%
Pacific |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 421.3 | $ 427.7
Percent of Total | 19.10% | 19.30%
Apartment |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 380.0 | $ 360.0
Percent of Total | 17.30% | 16.30%
Industrial |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 584.9 | $ 601.2
Percent of Total | 26.60% | 27.20%
Office |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 674.5 | $ 692.3
Percent of Total | 30.60% | 31.30%
Retail |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 529.5 | $ 527.6
Percent of Total | 24.10% | 23.80%
Other Property |  |
Mortgage Loans on Real Estate |  |
Mortgage Loans | $ 31.9 | $ 32.1
Percent of Total | 1.40% | 1.40%

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- Definition The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(c)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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