Securities - Summary of Carrying Amount and Estimated Fair Value of Held-to-Maturity Debt Securities and Amortized Cost and Estimated Fair Value of Available-for-Sale Debt Securities by Contractual Maturity (Parenthetical) (Details) (Other Debt Securities, USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Investments Classified By Contractual Maturity Date [Line Items]
Due after ten years	$ 101,572	[1]
Pooled trust preferred securities
Investments Classified By Contractual Maturity Date [Line Items]
Due after ten years	$ 247,000

[1] Consists of corporate bonds and capital trust notes. Included in capital trust notes are $247,000 of pooled trust preferred securities held to maturity, all of which are due after ten years. The remaining capital trust notes consist of single-issue trust preferred securities.