Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Components Of Comprehensive Income [Line Items]
Beginning balance			$ (395,657)	$ (586,769)
Unrealized holding gains (losses), net			(2,183)	145,809
Foreign currency translation adjustment			296	552
Total other comprehensive income before reclassifications			(1,887)	146,361
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			3,357	5,039
OTTI charges recognized in net income			9,800	33,331
Losses (gains) realized in net income			33,088	(9)
Amortization of gains on terminated cash flow hedges				(178)
Amortization of prior service credit			(5,936)	(4,904)
Amortization of actuarial losses			31,077	28,272
Total reclassifications			71,386	61,551
Total gain (loss) during the period			69,499	207,912
Ending balance	(326,158)	(378,857)	(326,158)	(378,857)
Beginning balance			155,393	230,328
Unrealized holding gains (losses), net			814	(57,183)
Foreign currency translation adjustment			(91)	(201)
Total other comprehensive income before reclassifications			723	(57,384)
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			(1,318)	(1,978)
OTTI charges recognized in net income			(3,847)	(13,082)
Losses (gains) realized in net income			(12,987)	4
Amortization of gains on terminated cash flow hedges				66
Amortization of prior service credit			2,330	1,925
Amortization of actuarial losses			(12,198)	(11,097)
Total reclassifications			(28,020)	(24,162)
Total gain (loss) during the period			(27,297)	(81,546)
Ending balance	128,096	148,782	128,096	148,782
Beginning balance			(240,264)	(356,441)
Unrealized holding gains (losses), net			(1,369)	88,626
Foreign currency translation adjustment	1,251	482	205	351
Total other comprehensive income before reclassifications			(1,164)	88,977
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			2,039	3,061
OTTI charges recognized in net income			5,953	20,249
Losses (gains) realized in net income			20,101	(5)
Amortization of gains on terminated cash flow hedges				(112)
Amortization of prior service credit			(3,606)	(2,979)
Amortization of actuarial losses			18,879	17,175
Total reclassifications			43,366	37,389
Total other comprehensive income	29,709	47,774	42,202	126,366
Ending Balance	(198,062)	(230,075)	(198,062)	(230,075)
Investment Securities With OTTI [Member]
Components Of Comprehensive Income [Line Items]
Beginning balance			(91,835)	(138,319)
Unrealized holding gains (losses), net			59,523	(8,099)
Foreign currency translation adjustment
Total other comprehensive income before reclassifications			59,523	(8,099)
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			230	1,544
OTTI charges recognized in net income			9,800	33,331
Losses (gains) realized in net income			41,217
Amortization of gains on terminated cash flow hedges
Amortization of prior service credit
Amortization of actuarial losses
Total reclassifications			51,247	34,875
Total gain (loss) during the period			110,770	26,776
Ending balance	18,935	(111,543)	18,935	(111,543)
Investment Securities All Other [Member]
Components Of Comprehensive Income [Line Items]
Beginning balance			152,199	9,757
Unrealized holding gains (losses), net			(61,706)	153,908
Foreign currency translation adjustment
Total other comprehensive income before reclassifications			(61,706)	153,908
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			3,127	3,495
OTTI charges recognized in net income
Losses (gains) realized in net income			(8,129)	(9)
Amortization of gains on terminated cash flow hedges
Amortization of prior service credit
Amortization of actuarial losses
Total reclassifications			(5,002)	3,486
Total gain (loss) during the period			(66,708)	157,394
Ending balance	85,491	167,151	85,491	167,151
Defined Benefit Plans [Member]
Components Of Comprehensive Income [Line Items]
Beginning balance			(455,590)	(457,145)
Unrealized holding gains (losses), net
Foreign currency translation adjustment
Total other comprehensive income before reclassifications
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities
OTTI charges recognized in net income
Losses (gains) realized in net income
Amortization of gains on terminated cash flow hedges
Amortization of prior service credit			(5,936)	(4,904)
Amortization of actuarial losses			31,077	28,272
Total reclassifications			25,141	23,368
Total gain (loss) during the period			25,141	23,368
Ending balance	(430,449)	(433,777)	(430,449)	(433,777)
Beginning balance			(276,771)
Total other comprehensive income			15,273
Ending Balance	(261,498)		(261,498)
Other [Member]
Components Of Comprehensive Income [Line Items]
Beginning balance			(431)	(1,062)
Unrealized holding gains (losses), net
Foreign currency translation adjustment			296	552
Total other comprehensive income before reclassifications			296	552
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities
OTTI charges recognized in net income
Losses (gains) realized in net income
Amortization of gains on terminated cash flow hedges				(178)
Amortization of prior service credit
Amortization of actuarial losses
Total reclassifications				(178)
Total gain (loss) during the period			296	374
Ending balance	$ (135)	$ (688)	$ (135)	$ (688)