Fair Value Measurements - Assets and Liabilities at Fair Value (Parenthetical) (Detail) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Fair Value Disclosures [Abstract]
Investments carried at cost	$ 10.0	$ 14.2	$ 16.6

Investments In Federal Home Loan Bank And First National Bankers Bank Stock At Cost

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