Valuation and Qualifying Accounts and Reserves (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for uncollectible accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 33,291	$ 36,794	$ 43,763
Charged to Expense	12,290	14,631	13,588
Deductions	15,580	18,134	20,557
Balance at End of Year	30,001	33,291	36,794
Valuation allowance for deferred tax assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	57,607	58,322	0
Charged to Expense	23,857	0	58,322
Deductions	0	715	0
Balance at End of Year	$ 81,464	$ 57,607	$ 58,322