Employee Benefit Plans (Schedule of Allocation of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	$ 255,642	$ 274,225
Other liabilities	(9,605)	(22,170)
Level 1
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	92,783	77,022
Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	128,645	156,015
Level 3
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	18,600	19,241
U.S. small-cap
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	5,064	13,520
U.S. small-cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	5,064	13,520
U.S. mid-cap
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	22,640	29,687
U.S. mid-cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	6,017	9,422
U.S. mid-cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	16,623	20,265
U.S. large-cap
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	43,232	70,226
U.S. large-cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	21,416	34,107
U.S. large-cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	21,816	36,119
Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	10,115	18,937
Non-U.S. | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	10,115	18,937
U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	66,922	26,519
U.S. government securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	60,286	19,973
U.S. government securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	6,636	6,546
Non-U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	4,050	1,567
Non-U.S. government securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	4,050	1,567
U.S. governement asset and mortgage backed securities
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	2,440	1,074
U.S. governement asset and mortgage backed securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	2,440	1,074
Corporate fixed income
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	54,679	58,191
Corporate fixed income | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	54,679	58,191
State and local government securities
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	3,829	6,406
State and local government securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	3,829	6,406
Other investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	27,057	26,151
Other investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	8,457	6,910
Other investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	18,600	19,241
Other fixed income
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	16,646	35,519
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	8,573	8,598
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	$ 240,028	$ 252,278