Components of Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance For Doubtful Accounts And Unbilled Services
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of period	$ 109,273		$ 94,048		$ 80,096
Charged to Expense	18,252		13,335		14,179
Charged to Other Accounts	35,423	[1]	20,463	[1]	13,054	[1]
Deductions	18,123	[2]	18,573	[2]	13,281	[2]
Balance at End of Period	144,825		109,273		94,048
Valuation Allowance of Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of period	10,201		1,939		886
Charged to Expense	4,241		8,262		1,053
Balance at End of Period	$ 14,442		$ 10,201		$ 1,939

[1] Includes estimated provision for unbilled services recorded as a reduction to revenues (i.e., fee, rate and other adjustments).

[2] Includes estimated direct write-offs of uncollectible and unrealizable accounts receivable.