Employee Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 4,592	$ 4,354	$ 0
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	28
Actual return on plan assets still held	280
Sales	(456)
Foreign currency translation	386
Other plan assets [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets		4,354
U.S. Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	617,840	562,564	552,817
Defined Benefit Plan Fair Value Of Plan Assets Gross	209,271	382,373
Business (dispositions) acquisitions	0	0
Foreign currency translation	0	0
U.S. Pension Plan, Defined Benefit [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,988	211,847
Defined Benefit Plan Fair Value Of Plan Assets Gross	3,988	211,847
U.S. Pension Plan, Defined Benefit [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	205,283	170,526
Defined Benefit Plan Fair Value Of Plan Assets Gross	205,283	170,526
U.S. Pension Plan, Defined Benefit [Member] | Equity - Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	161,426
U.S. Pension Plan, Defined Benefit [Member] | Equity - Domestic [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	161,426
U.S. Pension Plan, Defined Benefit [Member] | Equity - Domestic [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	43,272
U.S. Pension Plan, Defined Benefit [Member] | Mutual funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	43,272
U.S. Pension Plan, Defined Benefit [Member] | Mutual funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	74,509	60,638
U.S. Pension Plan, Defined Benefit [Member] | Corporate bonds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Corporate bonds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	74,509	60,638
U.S. Pension Plan, Defined Benefit [Member] | Government securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	133,540	115,789
U.S. Pension Plan, Defined Benefit [Member] | Government securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,766	5,901
U.S. Pension Plan, Defined Benefit [Member] | Government securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	130,774	109,888
U.S. Pension Plan, Defined Benefit [Member] | Private Placement [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,222	1,248
U.S. Pension Plan, Defined Benefit [Member] | Private Placement [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,222	1,248
U.S. Pension Plan, Defined Benefit [Member] | Private Placement [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Real estate funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	48,294	45,494
U.S. Pension Plan, Defined Benefit [Member] | Real estate funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Real estate funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	7,794	10,241
U.S. Pension Plan, Defined Benefit [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Collective funds at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	352,481	124,456
U.S. Pension Plan, Defined Benefit [Member] | Collective funds at NAV [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
U.S. Pension Plan, Defined Benefit [Member] | Collective funds at NAV [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	175,534	148,514	$ 159,436
Defined Benefit Plan Fair Value Of Plan Assets Gross	109,403	95,131
Business (dispositions) acquisitions	0	(3,967)
Foreign currency translation	10,491	(15,746)
Non-U.S. Pension Plans, Defined Benefit [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	67,469	68,807
Defined Benefit Plan Fair Value Of Plan Assets Gross	67,469	68,807
Non-U.S. Pension Plans, Defined Benefit [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	37,342	21,970
Defined Benefit Plan Fair Value Of Plan Assets Gross	37,342	21,970
Non-U.S. Pension Plans, Defined Benefit [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,592	4,354
Defined Benefit Plan Fair Value Of Plan Assets Gross	4,592	4,354
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	28,761	34,139
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stocks [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	28,761	34,139
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stocks [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stocks [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Fixed income investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	29,612	15,628
Non-U.S. Pension Plans, Defined Benefit [Member] | Fixed income investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Fixed income investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	29,612	15,628
Non-U.S. Pension Plans, Defined Benefit [Member] | Fixed income investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stock funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	38,717	35,175
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stock funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	34,075	31,203
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stock funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,642	3,972
Non-U.S. Pension Plans, Defined Benefit [Member] | Common stock funds [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,633	3,465
Non-U.S. Pension Plans, Defined Benefit [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,633	3,465
Non-U.S. Pension Plans, Defined Benefit [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Cash and Cash Equivalents [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Other plan assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	7,680	6,724
Non-U.S. Pension Plans, Defined Benefit [Member] | Other plan assets [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Other plan assets [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,088	2,370
Non-U.S. Pension Plans, Defined Benefit [Member] | Other plan assets [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,592	4,354
Non-U.S. Pension Plans, Defined Benefit [Member] | Collective funds at NAV [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	61,648	49,357
Non-U.S. Pension Plans, Defined Benefit [Member] | Collective funds at NAV [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Collective funds at NAV [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Collective funds at NAV [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Net Asset Value (NAV) Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,483	4,026
Non-U.S. Pension Plans, Defined Benefit [Member] | Net Asset Value (NAV) Other [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Net Asset Value (NAV) Other [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Non-U.S. Pension Plans, Defined Benefit [Member] | Net Asset Value (NAV) Other [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 0	$ 0