Segment Revenues and Segment Income (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Share-based compensation expense	$ 13,840	$ 12,038	$ 41,130	$ 36,510
Corporate and Other
Segment Reporting Information [Line Items]
Severance and other termination-related costs	13,300	5,000	61,100	39,100
Share-based compensation expense	$ 13,800	$ 12,000	$ 41,100	$ 36,500