Other Comprehensive Income/Loss (Amounts Reclassified From Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Gain on sales of securities	$ 86	$ 0
Compensation and benefits	(38,253)	(36,281)
Income before income tax expense	28,258	28,885
Income tax expense	(9,693)	(9,578)
Net income	18,565	19,307
Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Income before income tax expense	(628)	(804)
Income tax expense	254	306
Net income	(374)	(498)
Net unrealized gain on securities available-for-sale | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Gain on sales of securities	86	0
Net actuarial loss on pension plans and other postretirement benefits | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Compensation and benefits	(667)	(757)
Prior service cost on pension plans and other postretirement benefits | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Compensation and benefits	$ (47)	$ (47)