Reclassification out of accumulated other comprehensive income (loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended					6 Months Ended
	Jun. 30, 2014		Mar. 31, 2014	Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustment for (gains) losses included in net income (loss)	$ 0	[1]	$ (7,700)	$ 0	[1]	$ (7,718)	$ 0
Net Income	(511,314)			327,468		(424,905)	207,161
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net Income	(1,815)			(1,076)		(11,364)	(5,288)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest	(1,176)			(6,169)		(2,352)	(12,338)
Income Tax Expense Benefit	459			2,962		917	4,813
Net Income	(717)			(3,207)		(1,435)	(7,525)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Defined Benefit Plan Amortization Of Gains Losses [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Personnel costs	(2,126)			(6,169)		(4,252)	(12,338)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Defined Benefit Plan Amortization Of Prior Service Cost Credit [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Personnel costs	950			0		1,900	0
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges [Member] | Forward Contracts [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest	(1,800)			3,045		(3,624)	3,196
Mortgage banking activities	(1,800)			3,045		(3,624)	3,196
Income Tax Expense Benefit	702			(914)		1,413	(959)
Net Income	(1,098)			2,131		(2,211)	2,237
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Accumulated Translation Adjustment
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net Income	0			0		(7,718)	0
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Accumulated Translation Adjustment | Cumulative Translation Adjustment Reclassified Into Earnings [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest	0			0		(7,718)	0
Noninterest Income Other Operating Income	$ 0			$ 0		$ (7,718)	$ 0

[1] All amounts presented are net of tax.