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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Components Of Comprehensive Income [Line Items]
Beginning balance			$ (395,657)	$ (586,769)
Unrealized holding gains (losses), net			(39,694)	82,305
Foreign currency translation adjustment			(1,644)	(208)
Total other comprehensive income before reclassifications			(41,338)	82,097
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			2,371	3,807
OTTI charges recognized in net income			9,800	27,659
Losses (gains) realized in net income			33,088	363
Amortization of gains on terminated cash flow hedges				(178)
Amortization of prior service credit			(3,957)	(3,269)
Amortization of actuarial losses			20,718	18,848
Total reclassifications			62,020	47,230
Total gain (loss) during the period			20,682	129,327
Ending balance	(374,975)	(457,442)	(374,975)	(457,442)
Beginning balance			155,393	230,328
Unrealized holding gains (losses), net			15,557	(32,268)
Foreign currency translation adjustment			598	77
Total other comprehensive income before reclassifications			16,155	(32,191)
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			(931)	(1,494)
OTTI charges recognized in net income			(3,847)	(10,856)
Losses (gains) realized in net income			(12,987)	(145)
Amortization of gains on terminated cash flow hedges				66
Amortization of prior service credit			1,553	1,283
Amortization of actuarial losses			(8,132)	(7,398)
Total reclassifications			(24,344)	(18,544)
Total gain (loss) during the period			(8,189)	(50,735)
Ending balance	147,204	179,593	147,204	179,593
Beginning balance			(240,264)	(356,441)
Unrealized holding gains (losses), net			(24,137)	50,037
Foreign currency translation adjustment	(114)	(533)	(1,046)	(131)
Total other comprehensive income before reclassifications			(25,183)	49,906
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			1,440	2,313
OTTI charges recognized in net income			5,953	16,803
Losses (gains) realized in net income			20,101	218
Amortization of gains on terminated cash flow hedges		(42)		(112)
Amortization of prior service credit			(2,404)	(1,986)
Amortization of actuarial losses			12,586	11,450
Total reclassifications			37,676	28,686
Total other comprehensive income	(1,818)	53,409	12,493	78,592
Ending Balance	(227,771)	(277,849)	(227,771)	(277,849)
Investment Securities With OTTI [Member]
Components Of Comprehensive Income [Line Items]
Beginning balance			(91,835)	(138,319)
Unrealized holding gains (losses), net			55,473	(10,872)
Foreign currency translation adjustment
Total other comprehensive income before reclassifications			55,473	(10,872)
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			109	1,497
OTTI charges recognized in net income			9,800	27,659
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			51,126	29,156
Total gain (loss) during the period			106,599	18,284
Ending balance	14,764	(120,035)	14,764	(120,035)
Investment Securities All Other [Member]
Components Of Comprehensive Income [Line Items]
Beginning balance			152,199	9,757
Unrealized holding gains (losses), net			(95,167)	93,177
Foreign currency translation adjustment
Total other comprehensive income before reclassifications			(95,167)	93,177
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities			2,262	2,310
OTTI charges recognized in net income
Losses (gains) realized in net income			(8,129)	363
Amortization of gains on terminated cash flow hedges
Amortization of prior service credit
Amortization of actuarial losses
Total reclassifications			(5,867)	2,673
Total gain (loss) during the period			(101,034)	95,850
Ending balance	51,165	105,607	51,165	105,607
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			(3,957)	(3,269)
Amortization of actuarial losses			20,718	18,848
Total reclassifications			16,761	15,579
Total gain (loss) during the period			16,761	15,579
Ending balance	(438,829)	(441,566)	(438,829)	(441,566)
Beginning balance			(276,771)
Total other comprehensive income			10,182
Ending Balance	(266,589)		(266,589)
Other [Member]
Components Of Comprehensive Income [Line Items]
Beginning balance			(431)	(1,062)
Unrealized holding gains (losses), net
Foreign currency translation adjustment			(1,644)	(208)
Total other comprehensive income before reclassifications			(1,644)	(208)
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			(1,644)	(386)
Ending balance	$ (2,075)	$ (1,448)	$ (2,075)	$ (1,448)