Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 46,719	$ 41,166	$ 97,465	$ 116,154
Other comprehensive income:
Net change in unrealized (loss) gain on available for sale securities and hedges	(5,604)	15,131	39,997	2,174
Reclassification adjustment for net losses realized and included in earnings	1,158	802	2,960	2,208
Valuation adjustment for employee benefit plans	(6,347)	4,963	(6,347)	(959)
Amortization of unrealized net loss on securities transferred to held to maturity	1,108	1,023	2,736	2,609
Other comprehensive (loss) income before income taxes	(9,685)	21,919	39,346	6,032
Income tax (benefit) expense	(3,537)	8,002	14,440	2,125
Other comprehensive (loss) income net of income taxes	(6,148)	13,917	24,906	3,907
Comprehensive income	$ 40,571	$ 55,083	$ 122,371	$ 120,061