Borrowings - Summary of Average Balances, Weighted Average Interest Rates and Maximum Month-End Outstanding Amounts of Company's Borrowings (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Short-Term [Member]
Line of Credit Facility [Line Items]
Average balance	$ 26,738	$ 45,619	$ 49,678
Weighted average interest rate (for the year)	0.10%	0.20%	0.50%
Weighted average interest rate (at year end)	0.10%	0.30%	0.30%
Maximum month-end outstanding amount	34,379	56,312	61,897
Other Borrowings [Member]
Line of Credit Facility [Line Items]
Average balance	16,407	16,446	40,184
Weighted average interest rate (for the year)	4.40%	4.40%	4.40%
Weighted average interest rate (at year end)	4.40%	4.40%	4.40%
Maximum month-end outstanding amount	$ 16,425	$ 16,463	$ 87,748