Employee Benefit Plans (Projected Benefit Obligation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in projected benefit obligation:
Benefit obligation at beginning of period	$ 65,108	$ 61,256
Service costs	0	90	$ 161
Interest costs	1,879	2,587	1,205
Actuarial (gains)/losses	3,579	1,817
Benefits paid	(39,185)	(2,989)
Annuity carrier load	0	2,347
Projected benefit obligation at end of period	31,381	65,108	61,256
Change in plan assets:
Plan assets at fair value at beginning of period	25,225	21,175
Actual return on plan assets	(197)	(458)
Company contributions	14,157	7,497
Benefits paid	(39,185)	(2,989)
Plan assets at fair value at beginning of period	0	25,225	$ 21,175
Unfunded status of the plans	(31,381)	(39,883)
Accrued salaries and benefits	(1,513)	(10,604)
Other liabilities	(29,868)	(29,279)
Amounts recognized in the balance sheet	(31,381)	(39,883)
Amounts recognized in accumulated other comprehensive income/(loss):
Unrecognized net actuarial loss	12,184	14,021
Unrecognized prior service credit	(3,341)	(4,486)
Pension and other postretirement benefit plans, amount recognized in accumulated other comprehensive income	$ 8,843	$ 9,535