Defined Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Components of net periodic benefit cost included in employee compensation and benefits
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	53	66	106	138
Expected return on plan assets	(59)	(65)	(116)	(136)
Amortization of (loss) / gain	0	0	0	0
Amortization of prior service cost	5	5	10	10
Effect of settlement	(1)	(18)	(3)	(31)
Net periodic benefit cost	$ (2)	$ (12)	$ (3)	$ (19)