This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting.

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-Name Accounting Standards Codification

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Amount of the cost of borrowed funds accounted for as interest expense.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Topic 835

-SubTopic 20

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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

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-Name Accounting Standards Codification

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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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-Section S99

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Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other than temporary impairment									$ (565)	$ (1,833)	$ (2,509)
Realized gains, net									15,478us-gaap_RealizedInvestmentGainsLosses	25,259us-gaap_RealizedInvestmentGainsLosses	54,921us-gaap_RealizedInvestmentGainsLosses
Total interest expense	23,903us-gaap_InterestExpense	23,350us-gaap_InterestExpense	21,151us-gaap_InterestExpense	19,059us-gaap_InterestExpense	19,528us-gaap_InterestExpense	21,725us-gaap_InterestExpense	21,416us-gaap_InterestExpense	18,302us-gaap_InterestExpense	87,463us-gaap_InterestExpense	80,971us-gaap_InterestExpense	120,705us-gaap_InterestExpense
Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Investment Gain (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other than temporary impairment									565	499
Realized gains, net									(10,552)	20,008
Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Investment Gain (Loss) \| Gain on sale of AFS securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of AFS securities									(11,117)	19,509
Reclassification out of Accumulated Other Comprehensive Income \| Net unrealized losses on interest rate agreements accounted for as cash flow hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total interest expense									164	(281)
Reclassification out of Accumulated Other Comprehensive Income \| Net unrealized losses on interest rate agreements accounted for as cash flow hedges \| Unrealized Gain Loss On Derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total interest expense									$ 164	$ (281)