Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Nov. 14, 2017 USD ($)	Sep. 30, 2017	Aug. 31, 2017 USD ($)	Nov. 14, 2014 USD ($)
Significant Accounting Policies [Line Items]
Cost of sales for equipment sold		$ 96,800,000	$ 91,600,000	$ 84,100,000
Number of reportable segments | segment		2
Maximum allocation period (in year)		1 year
Reclassification of foreign currency translation loss to investment, net of tax		$ (31,381,000)	0	0
Capitalized computer software costs		37,400,000	33,100,000	23,400,000
Capitalized computer software amortization expense		$ 21,800,000	17,700,000	11,600,000
Minimum percentage of likelihood required to recognize uncertain income tax position		50.00%
Provisional income tax benefit due to corporate rate reduction		$ 210,000,000
Transition tax		$ 81,800,000
Maturity of cash equivalent, max (in months)		3 months
Foreign exchange gain (loss) recognized		$ (200,000)	(2,800,000)	(2,400,000)
Deferred financing costs	$ 13,100,000	16,300,000	13,100,000
Maximum undivided ownership interest pooled accounts receivable amount sold		950,000,000
Short-term debt outstanding	591,000,000	811,000,000	591,000,000
Advertising expense		26,100,000	22,200,000	19,900,000
Securitization Facility
Significant Accounting Policies [Line Items]
Payments of debt issuance costs								$ 1,700,000
Deferred financing costs							$ 10,600,000
Securitization Facility | Second Amendment
Significant Accounting Policies [Line Items]
Securitized accounts receivable facility		950,000,000			$ 950,000,000
New Credit Facility
Significant Accounting Policies [Line Items]
Payments of debt issuance costs	2,300,000	$ 12,900,000	$ 2,300,000
Minimum
Significant Accounting Policies [Line Items]
Threshold period during which company ceases billing and accruing late fees		30 days
Minimum | Stock options
Significant Accounting Policies [Line Items]
Period of vesting provisions (in years)		1 year
Minimum | Restricted Stock And Restricted Stock Units
Significant Accounting Policies [Line Items]
Period of vesting provisions (in years)		1 year
Maximum
Significant Accounting Policies [Line Items]
Threshold period during which company ceases billing and accruing late fees		40 days
Customer payment terms (in days)		14 days
Term of derivative contract		1 year
Maximum | Stock options
Significant Accounting Policies [Line Items]
Period of vesting provisions (in years)		5 years
Maximum | Restricted Stock And Restricted Stock Units
Significant Accounting Policies [Line Items]
Period of vesting provisions (in years)		3 years
Customer Concentration Risk
Significant Accounting Policies [Line Items]
Period past due for accounts receivable deemed as uncollectible		90 days
Period past due for allowance of trade accounts receivable maximum		90 days
Customer Concentration Risk | Accounts Receivable
Significant Accounting Policies [Line Items]
Concentration risk, percentage		96.00%	95.00%
Masternaut
Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage						44.00%
Non-cash impairment charge on equity method investment	$ 36,100,000	$ 44,600,000	$ 36,100,000	$ 40,000,000
Reclassification of foreign currency translation loss to investment, net of tax		$ (31,400,000)