Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Examination [Line Items]
New York City unincorporated business tax rate	4.00%
Total amount of interest expense (credit) recorded in income tax expense	$ 400,000	$ 400,000	$ 100,000
Accrued interest recorded on the consolidated statements of financial condition	1,000,000	600,000	200,000
Accrued penalties recorded on the consolidated statements of financial condition	$ 0	0	0
Minimum years that remain open and may be subject to examination vary under local law	1 year
Maximum years that remain open and may be subject to examination vary under local law	7 years
Accumulated undistributed earnings	$ 892,000,000
Additional taxes not provided	74,800,000
Unrecognized tax benefits	12,004,000	$ 11,311,000	$ 2,975,000	$ 3,672,000
City of New York [Member]
Income Tax Examination [Line Items]
Unrecognized tax benefits	$ 5,500,000