Accumulated Other Comprehensive Income (Reclassification out of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment securities gains, net	$ 0	$ 0	$ 462	$ 62
Compensation and employee benefits	33,287	21,523	90,597	64,484
Total before tax	20,010	16,535	59,126	44,901
Income tax provision	(6,734)	(4,655)	(19,083)	(12,220)
Net Income	13,276	11,880	40,043	32,681
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains and Losses on Available-for-Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment securities gains, net	0		462
Total before tax	0		462
Income tax provision	0		(163)
Net Income	0		299
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains and Losses on Pension Plan Liability [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Compensation and employee benefits	(92)		(276)
Total before tax	(92)		(276)
Income tax provision	33		98
Net Income	$ (59)		$ (178)