Fair Value of Financial Assets and Liabilities - Changes in Level 3 Contingent Consideration Measured at Fair Value on Recurring Basis (Detail) - Accounts Payable Accrued and Other Liabilities [Member] - Contingent Consideration [Member] - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening Balance	$ 52,737	$ 64,337	$ 55,614	$ 65,043
Total realized and unrealized gains (losses) included in Net income(loss)	(2,727)	(749)	(3,769)	(748)
Unrealized gains (losses) included in Other comprehensive income (loss)	(1,115)	80	(1,159)	78
Issuances	2,172	578	8,363	1,411
Settlements	(355)	(3,312)	(10,509)	(4,852)
Closing Balance	58,396	62,272	58,396	62,272
Unrealized gains (losses) for Level 3 Assets / Liabilities Outstanding	$ (3,842)	$ (699)	$ (4,929)	$ (670)