Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stockholders' Equity [Abstract]
Unrecognized prior service cost and net actuarial loss on pension plans	$ (18,227)	$ (21,557)
Unrealized losses on derivatives (cash flow hedges)	1,772	0
Unrealized net holding (losses) gains on AFS securities	(5,065)	(861)
Accumulated other comprehensive (loss)	$ (21,520)	$ (22,418)
Class of Warrant or Right [Line Items]
Preceding period of retained net profits for approval of Office of Comptroller of the Currency	2 years
Statutory amount available for dividend payments	$ 102,500
Common stock repurchased during period (in shares)	675,535	1,047,152	3,288
Common stock repurchased during period	$ 17,200
Treasury stock acquired, average cost per share (in dollars per share)	$ 25.45
Number of shares available for repurchase under stock repurchase program (in shares)	1,000,000