Short-Term Borrowings (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt [Line Items]
Line of credit with a major domestic bank		$ 25,000
Outstanding line of credit		$ 10,000
Weighted average interest rates on short-term borrowings	0.53%	0.84%	1.04%
Weighted average interest rates on short-term borrowings	0.47%	0.71%	1.00%