Proxy Contest (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) director	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) director	Jun. 30, 2017 USD ($)
Other Income and Expenses [Abstract]
Number of directors nominated by shareholder | director	5		5
Number of directors | director	8		8
Schedule of Professional Fees by Component
Proxy contest | $	$ 7,191	$ 0	$ 7,598	$ 0
Strategic review and other costs
Schedule of Professional Fees by Component
Proxy contest | $	$ 7,200		$ 7,600