Changes to Accumulated Other Comprehensive Income (Loss) by Component (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period			$ 148,766
Total other comprehensive income (loss)	(7,786)	(3,515)	11,005	(23,564)
Balance at End of Period	159,771		159,771
Net unrealized gains on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	197,542	145,349	164,654	186,580
Other comprehensive income (loss) before reclassifications	1,849	(633)	35,078	(29,615)
Amounts reclassified from other accumulated comprehensive income	(6,409)	(6,962)	(6,750)	(19,211)
Total other comprehensive income (loss)	(4,560)	(7,595)	28,328	(48,826)
Balance at End of Period	192,982	137,754	192,982	137,754
Net unrealized losses on interest rate agreements accounted for as cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(29,985)	(27,066)	(15,888)	(48,248)
Other comprehensive income (loss) before reclassifications	(3,258)	4,018	(17,454)	25,043
Amounts reclassified from other accumulated comprehensive income	32	62	131	219
Total other comprehensive income (loss)	(3,226)	4,080	(17,323)	25,262
Balance at End of Period	$ (33,211)	$ (22,986)	$ (33,211)	$ (22,986)

- Definition

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.

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