Segment Reporting, Geographic and Customer Information - Geographic Information by Organizational Region (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
Revenue:
REVENUE	$ 568,430	$ 574,448	$ 571,891	$ 565,490	$ 562,938	$ 568,197	$ 552,319	$ 535,140	$ 2,280,259	$ 2,218,594	$ 2,120,972
Long-Lived Assets:
Long-Lived Assets	2,869,107				2,883,077				2,869,107	2,883,077	2,467,869
Americas-United States [Member]
Revenue:
REVENUE									1,812,068	1,716,667	1,621,672
Long-Lived Assets:
Long-Lived Assets	2,650,801				2,686,553				2,650,801	2,686,553	2,242,572
Europe, Middle East & Africa (EMEA) [Member]
Revenue:
REVENUE									310,805	324,466	311,774
Long-Lived Assets:
Long-Lived Assets	195,203				176,817				195,203	176,817	204,282
Asia-Pacific [Member]
Revenue:
REVENUE									141,849	153,628	163,946
Long-Lived Assets:
Long-Lived Assets	21,151				17,891				21,151	17,891	18,456
Americas-Other [Member]
Revenue:
REVENUE									15,537	23,833	23,580
Long-Lived Assets:
Long-Lived Assets	$ 1,952				$ 1,816				$ 1,952	$ 1,816	$ 2,559