Other Income (Loss) - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Anthem
Schedule Of Other Nonoperating Income Expense [Line Items]
Proceeds from sales / distributions of ownership interests	$ 1.0
Acquirgy
Schedule Of Other Nonoperating Income Expense [Line Items]
Loan repayment from equity / cost method investment	0.4
StarCite
Schedule Of Other Nonoperating Income Expense [Line Items]
Proceeds from sales / distributions of ownership interests		$ 0.3