Short-Term Borrowings and Long-Term Debt - Additional Information (Detail) (USD $)	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Debt Disclosure [Line Items]
Interest expense, debt	$ 5,792,000	$ 5,794,000
Weighted average interest rates associated with short-term borrowings	0.06%
Federal Home Loan Bank Advances \| San Francisco
Debt Disclosure [Line Items]
Market value of collateral pledged	1,400,000,000
Federal Reserve Bank Advances
Debt Disclosure [Line Items]
Market value of collateral pledged	$ 562,000,000

Weighted average interest rate of short-term debt outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Subparagraph b

-Article 5

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