Commitments, Guarantees and Other Contingencies - Schedule of Contractual Obligations of Time Deposit Accounts (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Contractual Obligation Fiscal Year Maturity [Line Items]
Less than one year	$ 323,267
Over one through three years	38,946
Over three through five years	8,506
Over five years	10,508
Total	381,227
Real property operating lease obligations [Member]
Contractual Obligation Fiscal Year Maturity [Line Items]
Less than one year	1,705
Over one through three years	3,463
Over three through five years	3,308
Over five years	10,441
Total	18,917
Time deposit accounts [Member]
Contractual Obligation Fiscal Year Maturity [Line Items]
Less than one year	301,327
Over one through three years	32,951
Over three through five years	4,709
Over five years	57
Total	339,044
Contractually required interest payments on time deposits [Member]
Contractual Obligation Fiscal Year Maturity [Line Items]
Less than one year	20,235
Over one through three years	2,532
Over three through five years	489
Over five years	10
Total	$ 23,266