Employee Benefit Plans Employee Benefits Plan (Fair value of plan assets - level 3 utilization) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Balance, January 1	$ 453,087	$ 427,131	$ 443,962
Actual return on plan assets	43,271	(593)
Value of plan assets, December 31	453,087	427,131
Limited partnership interests | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Balance, January 1	1,316	0	$ 0
Actual return on plan assets	54	0
Settlements	(213)
Transfers into Level 3 (1)	1,475
Value of plan assets, December 31	$ 1,316	$ 0