Derivative - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Interest rate swap agreement notional amount		$ 1,340,000
LIBOR rate period		30 days
Reference Rate Maturity Duration	10 years	10 years
Derivative instrument maturity date	Dec. 22, 2022
Interest rate description	30-day LIBOR rate plus 1.95% to a fixed rate of 3.90% for the 10-year period through December 22, 2022.
Fair value of derivative agreement	56,000	41,000
Other comprehensive income (loss)	(9,466)	(20,342)	7,448
Income tax expense (benefit) on derivative	(4,877)	(10,479)	3,837
Minimum [Member]
Derivatives, Fair Value [Line Items]
Interest Rate Description, Lower Fixed Interest Rate Range		1.95%
Maximum [Member]
Derivatives, Fair Value [Line Items]
Interest Rate Description, Higher Fixed Interest Rate Range		3.90%
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Interest Rate Description, Lower Fixed Interest Rate Range		1.75%
Interest Rate Description, Higher Fixed Interest Rate Range		4.95%
Realized gains (losses) on investments in 2003 interest Swap Agreement		(5,900)
Other comprehensive income (loss)	(9,466)	(16,447)	7,448
Income tax expense (benefit) on derivative	(4,877)	(8,474)	3,837
Interest Rate Swap [Member] | Minimum [Member]
Derivatives, Fair Value [Line Items]
Interest rate swap agreement notional amount		1,500,000
Interest Rate Swap [Member] | Maximum [Member]
Derivatives, Fair Value [Line Items]
Interest rate swap agreement notional amount		$ 1,800,000