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Securities - Securities with Unrealized Losses Aggregated by Investment Category and Length of Time (Detail) (USD $) | Dec. 31, 2013 | Dec. 31, 2012
--- | --- | ---
Schedule of Available-for-sale Securities [Line Items] |  |
Fair Value, Less than 12 Months | $ 58,767,000 | $ 33,555,000
Unrealized Loss, Less than 12 Months | 5,833,000 | 388,000
Fair Value, 12 Months or More | 29,679,000 | 0
Unrealized Loss, 12 Months or More | 4,267,000 | 0
Fair Value | 88,446,000 | 33,555,000
Unrealized Loss | 10,100,000 | 388,000
U.S. Government agency debt obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair Value, Less than 12 Months | 57,117,000 | 33,555,000
Unrealized Loss, Less than 12 Months | 5,798,000 | 388,000
Fair Value, 12 Months or More | 29,679,000 | 0
Unrealized Loss, 12 Months or More | 4,267,000 | 0
Fair Value | 86,796,000 | 33,555,000
Unrealized Loss | 10,065,000 | 388,000
Mortgage-backed securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair Value, Less than 12 Months | 0 | 0
Unrealized Loss, Less than 12 Months | 0 | 0
Fair Value, 12 Months or More | 0 | 0
Unrealized Loss, 12 Months or More | 0 | 0
Fair Value | 0 | 0
Unrealized Loss | 0 | 0
Michigan Strategic Fund bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair Value, Less than 12 Months | 0 | 0
Unrealized Loss, Less than 12 Months | 0 | 0
Fair Value, 12 Months or More | 0 | 0
Unrealized Loss, 12 Months or More | 0 | 0
Fair Value | 0 | 0
Unrealized Loss | 0 | 0
Municipal general obligation bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair Value, Less than 12 Months | 295,000 | 0
Unrealized Loss, Less than 12 Months | 4,000 | 0
Fair Value, 12 Months or More | 0 | 0
Unrealized Loss, 12 Months or More | 0 | 0
Fair Value | 295,000 | 0
Unrealized Loss | 4,000 | 0
Municipal revenue bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair Value, Less than 12 Months | 0 | 0
Unrealized Loss, Less than 12 Months | 0 | 0
Fair Value, 12 Months or More | 0 | 0
Unrealized Loss, 12 Months or More | 0 | 0
Fair Value | 0 | 0
Unrealized Loss | 0 | 0
Mutual funds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair Value, Less than 12 Months | 1,355,000 | 0
Unrealized Loss, Less than 12 Months | 31,000 | 0
Fair Value, 12 Months or More | 0 | 0
Unrealized Loss, 12 Months or More | 0 | 0
Fair Value | 1,355,000 | 0
Unrealized Loss | $ 31,000 | $ 0

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- Definition Available for sale securities continuous unrealized loss position aggregate losses accumulated in investments. + References No definition available. + Details
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- Definition Available-for-sale securities continuous unrealized loss position less than twelve months aggregate losses accumulated in investments. + References No definition available. + Details
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- Definition Available for sale securities continuous unrealized loss position twelve months or longer aggregate losses accumulated in investments. + References No definition available. + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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