Description of Business and Summary of Significant Accounting Policies (Narrative) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Depreciation and Amortization
Depreciation expense	$ 1,700,000	$ 2,300,000	$ 6,000,000
Deferred Costs
Impairment of ongoing project, deferred costs		0
Advertising Expense
Advertising expense	$ 4,300,000	$ 4,500,000	$ 6,100,000
Equipment and Software | Minimum
Depreciation and Amortization
Useful life	3 years
Equipment and Software | Maximum
Depreciation and Amortization
Useful life	5 years