Description of Business and Summary of Significant Accounting Policies (Narrative) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Depreciation and Amortization
Depreciation expense	$ 6,000,000	$ 8,100,000	$ 8,500,000
Deferred Costs
Impairment of ongoing project, deferred costs	0	0	700,000
Advertising Expense
Advertising expense	$ 6,100,000	$ 16,500,000	$ 23,100,000
Equipment and Software | Minimum
Depreciation and Amortization
Useful life	3 years
Equipment and Software | Maximum
Depreciation and Amortization
Useful life	5 years