Securities - Summary of Portfolio of Securities Held to Maturity (Parenthetical) (Details) (Held-to-maturity Securities, USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Held-to-maturity Securities
Schedule of Held-to-maturity Securities [Line Items]
Non-credit portion of OTTI recorded in AOCL, before taxes	$ 8.9	$ 9.2

Accumulated Other Comprehensive Income Loss Noncredit Portion of Other Than Temporarily Impaired Securities Before Tax

No definition available.

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