Revenue and Long-Lived Assets for Each of Geographic Areas (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 183,045	$ 187,942	$ 198,909	$ 177,822	$ 173,357	$ 204,824	$ 242,745	$ 236,990	$ 747,718	$ 857,916	$ 832,022
Property, Plant and Equipment	78,876				83,304				78,876	83,304	76,672
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									557,389	674,106	611,240
Property, Plant and Equipment	63,404				67,821				63,404	67,821	69,438
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									50,281	57,623	71,389
Property, Plant and Equipment	2,329				2,890				2,329	2,890	3,353
All Other Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									140,048	126,187	149,393
Property, Plant and Equipment	$ 13,143				$ 12,593				$ 13,143	$ 12,593	$ 3,881