Accumulated Other Comprehensive Income (Reclassification out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment securities gains, net			$ 602	$ 1,064
Compensation and employee benefits	$ 37,291	$ 38,446	73,610	77,546
Total before tax	36,650	31,799	67,138	66,987
Income tax provision	(11,245)	(9,853)	(20,474)	(20,680)
Net income	25,405	21,946	46,664	46,307
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	229	343	602	1,064
Total before tax	229	343	602	1,064
Income tax provision	(83)	(124)	(218)	(386)
Net income	146	219	384	678
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	(167)	(98)	(334)	(142)
Total before tax	(167)	(98)	(334)	(142)
Income tax provision	61	35	122	51
Net income	$ (106)	$ (63)	$ (212)	$ (91)