Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Account receivable allowances	$ 6.6	$ 7.7
Accrued compensation and benefits	12.5	14.6
Deferred revenue	8.0	6.7
Legal and professional fees	10.7	10.4
Restructuring	1.2	2.3
Other	3.0	3.5
Total current	42.0	45.2
Accumulated depreciation and amortization	0.9	0.9
Stock-based compensation	56.1	62.3
Benefit plans	101.6	108.7
Deferred rent and construction allowance	28.5	30.5
Deferred revenue	35.8	34.2
Foreign net operating loss	3.7	7.5
Uncertain tax positions	38.2	38.3	$ 195.6
Self-insured related reserves	22.7	14.9
Other	4.4	5.6
Total non-current	291.9	302.9
Total deferred tax assets	333.9	348.1
Deferred tax liabilities:
Compensation and benefits	(3.0)	(3.0)
Unrealized gains on net investment hedges	(24.2)	(14.0)
Other	(1.5)	(1.1)
Total current	(28.7)	(18.1)
Accumulated depreciation and amortization of intangible assets and capitalized software	(203.0)	(204.3)
Foreign earnings to be repatriated	(2.9)	(3.4)
Self-insured related income	(22.7)	(16.9)
Other	(5.8)	(0.1)
Total non-current	(234.4)	(224.7)
Total deferred tax liabilities	(263.1)	(242.8)
Net deferred tax asset	70.8	105.3
Valuation allowance	(4.3)	(6.9)	$ 8.4	$ 15.2
Total net deferred tax assets	$ 66.5	$ 98.4