Pension and Other Postretirement Benefits - Fair Value Hierarchy - Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets excluding assets measured at NAV	$ 86,591	$ 119,583
Fair Value of Plan Assets measured at NAV	49,450	3,274
Fair Value of Plan Assets	136,041	122,857
Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,711	35,407
Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	10,061	19,379
Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	74,819	64,797	$ 72,895
Insurance Contract [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	72,778	62,409	72,417
Real Estate Fund [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,041	2,388	478
Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets excluding assets measured at NAV	1,581	45,309
Fair Value of Plan Assets	49,197	46,701	49,689
Domestic [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,581	35,400
Domestic [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	9,909
Domestic [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Domestic [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	302	753
Domestic [Member] | Cash and Cash Equivalents [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	302	753
Domestic [Member] | Cash and Cash Equivalents [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Domestic [Member] | Cash and Cash Equivalents [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Domestic [Member] | Equity Securities Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		13,346
Domestic [Member] | Equity Securities Large Cap [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		13,346
Domestic [Member] | Equity Securities Large Cap [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Securities Large Cap [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Funds Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		6,363
Domestic [Member] | Equity Funds Large Cap [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		6,363
Domestic [Member] | Equity Funds Large Cap [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Funds Large Cap [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Securities Small Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,279	773
Domestic [Member] | Equity Securities Small Cap [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,279	773
Domestic [Member] | Equity Securities Small Cap [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Domestic [Member] | Equity Securities Small Cap [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Domestic [Member] | Equity Funds Small Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		2,333
Domestic [Member] | Equity Funds Small Cap [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		2,333
Domestic [Member] | Equity Funds Small Cap [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Funds Small Cap [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Funds International Developed And Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		5,166
Domestic [Member] | Equity Funds International Developed And Emerging Markets [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		5,166
Domestic [Member] | Equity Funds International Developed And Emerging Markets [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Funds International Developed And Emerging Markets [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Securities International Developed And Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		2,519
Domestic [Member] | Equity Securities International Developed And Emerging Markets [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		2,519
Domestic [Member] | Equity Securities International Developed And Emerging Markets [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Equity Securities International Developed And Emerging Markets [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		9,601
Domestic [Member] | Corporate Debt Securities [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Corporate Debt Securities [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		9,601
Domestic [Member] | Corporate Debt Securities [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		4,147
Domestic [Member] | Fixed Income Funds [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		4,147
Domestic [Member] | Fixed Income Funds [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Fixed Income Funds [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Domestic And Foreign Government Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		308
Domestic [Member] | Domestic And Foreign Government Debt Securities [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Domestic And Foreign Government Debt Securities [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		308
Domestic [Member] | Domestic And Foreign Government Debt Securities [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		0
Domestic [Member] | Pooled Separate Accounts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets measured at NAV	1,431	1,392
Domestic [Member] | Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets measured at NAV	46,185
Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets excluding assets measured at NAV	85,010	74,274
Fair Value of Plan Assets	86,844	76,156	$ 86,523
Foreign [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	130	7
Foreign [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	10,061	9,470
Foreign [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	74,819	64,797
Foreign [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	130	7
Foreign [Member] | Cash and Cash Equivalents [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	130	7
Foreign [Member] | Cash and Cash Equivalents [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Cash and Cash Equivalents [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,753	2,290
Foreign [Member] | Fixed Income Funds [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Fixed Income Funds [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,753	2,290
Foreign [Member] | Fixed Income Funds [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Insurance Contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	72,778	62,409
Foreign [Member] | Insurance Contract [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Insurance Contract [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Insurance Contract [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	72,778	62,409
Foreign [Member] | Equity Funds Diversified [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	7,308	7,180
Foreign [Member] | Equity Funds Diversified [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Equity Funds Diversified [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	7,308	7,180
Foreign [Member] | Equity Funds Diversified [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Real Estate Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,041	2,388
Foreign [Member] | Real Estate Fund [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Real Estate Fund [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Foreign [Member] | Real Estate Fund [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,041	2,388
Foreign [Member] | Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets measured at NAV	$ 1,834	$ 1,882