Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) (Fixed rate long-term borrowings [Member], Fair Value Hedges [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Fixed rate long-term borrowings [Member] | Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 1,400,000	$ 1,400,000
Average Maturity (in years)	3 years 4 months 24 days	3 years 8 months 12 days
Weighted-Average Rate, Fixed	4.42%	4.42%
Weighted-Average Rate, Variable	1.19%	1.20%