Employee Benefit Plans - Summary of Changes in Benefit Obligations, Fair Value of Assets, Funded Status and Amounts Recognized in Consolidated Statements of Financial Condition (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in benefit obligation
Benefit obligation at beginning of year	$ 718,821
Benefit obligation at end of year	763,831	$ 718,821
Change in plan assets
Fair value of plan assets at beginning of year	646,119
Fair value of plan assets at end of year	728,281	646,119
Pension Plans [Member]
Change in benefit obligation
Benefit obligation at beginning of year	718,821	694,187
Service cost	1,413	1,235	$ 1,530
Interest cost	16,240	19,871	24,600
Actuarial (gain) loss	2,702	135,164
Benefits paid	(44,589)	(31,904)
Foreign currency translation and other adjustments	69,244	(99,732)
Benefit obligation at end of year	763,831	718,821	694,187
Change in plan assets
Fair value of plan assets at beginning of year	646,119	656,084
Actual return on plan assets	43,624	119,287	9,873
Employer contributions	16,844	11,343	39,301
Benefits paid	(42,022)	(29,384)	(32,321)
Foreign currency translation and other adjustments	63,716	(111,211)
Fair value of plan assets at end of year	728,281	646,119	656,084
Funded (deficit) at end of year	(35,550)	(72,702)
Prepaid pension asset (included in “other assets”)	16,189	822
Accrued benefit liability (included in “other liabilities”)	(51,739)	(73,524)
Net amount recognized	(35,550)	(72,702)
Actuarial net loss (gain)	184,135	192,855
Prior service cost		30
Net amount recognized	$ 184,135	192,885
Medical Plan [Member]
Change in benefit obligation
Benefit obligation at beginning of year		4,750
Service cost		11	27
Interest cost		167	179
Actuarial (gain) loss		(1,639)
Benefits paid		(3,289)
Benefit obligation at end of year			4,750
Change in plan assets
Employer contributions		3,289	276
Benefits paid		$ (3,289)	$ (276)