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Fair Value Measurements - Additional Information (Details) - USD ($) | 6 Months Ended
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Mar. 31, 2016 | Mar. 31, 2015
Fair Value Disclosures [Abstract] |  |
Proceeds on available-for-sale securities sold | $ 0 | $ 0
Term of contractual due dates of substantially all mortgage-backed securities | 10 years |

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- Definition The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26853-111562 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3179-108585 + Details
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- Definition Term of Contractual Due Dates of Substantially All Mortgage-Backed Securities + References No definition available. + Details
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