Schedule of Geographical Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Segment Reporting Information
Revenues	$ 215,702		$ 202,970		$ 427,897		$ 391,127
Long-lived assets	166,722	[1]	135,350	[1]	166,722	[1]	135,350	[1]
UNITED STATES
Segment Reporting Information
Revenues	132,081		120,152		256,051		232,899
Long-lived assets	129,057	[1]	113,636	[1]	129,057	[1]	113,636	[1]
IRELAND
Segment Reporting Information
Revenues	38,132		36,359		77,871		67,324
Long-lived assets	21,480	[1]	7,802	[1]	21,480	[1]	7,802	[1]
Other International
Segment Reporting Information
Revenues	45,489	[2]	46,459	[2]	93,975	[2]	90,904	[2]
Long-lived assets	$ 16,185	[1],[2]	$ 13,912	[1],[2]	$ 16,185	[1],[2]	$ 13,912	[1],[2]

[1] Includes property and equipment, net and other assets

[2] No single location within Other International accounts for greater than 10% of total revenues