Valuation and Qualifying Accounts (Detail) (Allowance for Doubtful Accounts, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 12,140	[1]	$ 11,994	[1]	$ 6,632	[1]
Additions Charged to Costs and Expenses	11,127	[1]	9,718	[1]	5,362	[1]
Deductions	(13,028)	[1]	(9,572)	[1]
Balance at End of Period	$ 10,239	[1]	$ 12,140	[1]	$ 11,994	[1]

[1] These amounts include reserves for bad debts.