Segment Reporting and Geographical Location - Revenue and Long-Lived Assets for Each of Geographic Areas (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 184,692	$ 202,729	$ 217,617	$ 220,303	$ 211,874	$ 213,802	$ 215,996	$ 198,071	$ 825,341	$ 839,743	$ 747,718
Long-lived Assets	70,961				73,462				70,961	73,462	78,876
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									635,627	644,547	557,389
Long-lived Assets	59,280				60,819				59,280	60,819	63,404
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									189,714	195,196	190,329
Long-lived Assets	$ 11,681				$ 12,643				$ 11,681	$ 12,643	$ 15,472