Retirement Plans - Summary of Fair Values of Pension Plan (Details 8) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair values of pension plan assets
Total fair value of plan assets	$ 290,795	$ 329,581
Equity Securities | U.S.
Fair values of pension plan assets
Total fair value of plan assets	56,696	174,153
Equity Securities | non-U.S.
Fair values of pension plan assets
Total fair value of plan assets	11,028	14,050
Equity Funds
Fair values of pension plan assets
Total fair value of plan assets	17,522	0
Equity Funds | U.S.
Fair values of pension plan assets
Total fair value of plan assets	0	13,077
Equity Funds | non-U.S.
Fair values of pension plan assets
Total fair value of plan assets	26,903	0
Equity Funds | International LP
Fair values of pension plan assets
Total fair value of plan assets	0	15,636
Corporate Bond
Fair values of pension plan assets
Total fair value of plan assets	0	47,417
Bond funds - government
Fair values of pension plan assets
Total fair value of plan assets	47,800	0
Bond funds - other
Fair values of pension plan assets
Total fair value of plan assets	69,617	0
Real estate
Fair values of pension plan assets
Total fair value of plan assets	10,006	0
Cash and Cash Equivalents
Fair values of pension plan assets
Total fair value of plan assets	7,417	5,889
Debt securities issued by U.S., states and local governments
Fair values of pension plan assets
Total fair value of plan assets	0	14,484
Partnership
Fair values of pension plan assets
Total fair value of plan assets	13,360	11,239
Long/short equity-focused hedge funds
Fair values of pension plan assets
Total fair value of plan assets	5,255	5,367
International hedge funds
Fair values of pension plan assets
Total fair value of plan assets	25,191	11,679
Mortgage-backed securities
Fair values of pension plan assets
Total fair value of plan assets	0	3,796
Fixed Annuities
Fair values of pension plan assets
Total fair value of plan assets	0	12,475
Other asset-backed securities
Fair values of pension plan assets
Total fair value of plan assets	$ 0	$ 319