Segment Information - Additional Information (Detail) - Hudson City [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Increase (decrease) in total revenues	$ 14
Increase (decrease) in net income	8
All Other [Member]
Segment Reporting Information [Line Items]
Increase (decrease) in total revenues	(14)
Increase (decrease) in net income	$ (8)