Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014
Repurchase of shares
Repurchase of common stock (in shares)	810,097us-gaap_TreasuryStockSharesAcquired	0us-gaap_TreasuryStockSharesAcquired
Aggregate cost of treasury shares purchase	$ 59,654
Pre-tax amounts:
Accumulated other comprehensive income (loss) before tax	65,851	134,433
After-tax amounts:
Accumulated other comprehensive income (loss)	41,078	83,126
Maximum
Repurchase of shares
Number of common shares authorized to be repurchased	4,000,000
Unrealized Appreciation (Depreciation) on Available-for-sale Securities
Pre-tax amounts:
Accumulated other comprehensive income (loss) before tax	88,947	157,838
After-tax amounts:
Accumulated other comprehensive income (loss)	55,174	97,418
Defined Benefit Pension Plan
Pre-tax amounts:
Accumulated other comprehensive income (loss) before tax	(23,096)	(23,405)
After-tax amounts:
Accumulated other comprehensive income (loss)	$ (14,096)	$ (14,292)

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Amount before tax of increase (decrease) in accumulated in equity from transactions and other events and circumstances from non-owner sources. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners).

+ References

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

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The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

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Number of shares that have been repurchased during the period and are being held in treasury.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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