Segment Reporting and Geographic Locations - Revenue and Long-Lived Assets for Each of Geographic Areas (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 149,966	$ 153,604	$ 178,251	$ 180,291	$ 184,692	$ 202,729	$ 217,617	$ 220,303	$ 662,112	$ 825,341	$ 839,743
Long-lived Assets	66,041				70,961				66,041	70,961	73,462
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									496,473	635,627	644,547
Long-lived Assets	54,334				59,280				54,334	59,280	60,819
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									165,639	189,714	195,196
Long-lived Assets	$ 11,707				$ 11,681				$ 11,707	$ 11,681	$ 12,643