Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Allowance For Doubtful Accounts [Abstract]
Beginning Balance	$ 6,001	$ 4,768	$ 4,544
Accounts written off	(34,723)	(30,609)	(25,178)
Bad debt expense	35,894	31,842	25,402
Ending Balance	$ 7,172	$ 6,001	$ 4,768