Retirement Plans - Funded status of plan by geographic location (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2015
Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	$ (42,786)	$ (42,763)
US Plan
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	(14,093)	(16,306)
UK Plans
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	(2,316)	(4,650)	$ (1,000)
Europe plans
Defined Benefit Plan Disclosure [Line Items]
Funded status - end of year	$ (26,377)	$ (21,807)