Restructuring Charges - Accrual for Severance and Related Costs (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Restructuring And Related Activities [Abstract]
Balance, Beginning of Period		$ 8,686	$ 18,985
Severance & Related Charges	[1],[2]		215
Payments		(1,889)	(5,325)
Non-cash Adjustments	[3]	(173)	478
Balance, End of Period		$ 6,624	$ 14,353

[1] Includes charges related to COBRA and outplacement services which are assumed to be completed by the third month following an employee’s departure.

[2] Severance charges will result in future cash payments through 2018.

[3] Includes cancellations due to employee departures prior to agreed upon end dates, employee transfers to open positions within the organization and subsequent adjustments to severance and related costs.