Supplemental Financial Statement Information - Additional Information (Detail) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Capitalized contract acquisition costs						$ 8,100,000
Amortization of deferred contract acquisition costs		$ 1,000,000		$ 2,100,000
Impairment loss of capitalized contract acquisition costs		0		0
Change in Capitalized Contract Cost		1,100,000		2,100,000
Deferred cost of revenue		400,000		400,000			$ 3,500,000
Aggregate minimum future rental revenues		7,006,000		7,006,000
Reclassified amounts out of AOCI, net of tax	[1]	$ (9,000)	$ 17,000	$ (11,000)	$ 22,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred sales commissions amortization period				3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred sales commissions amortization period				4 years

[1] Tax effects were less than $0.1 million for the periods presented above.