Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended	15 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 331	$ 1,435	$ 6,176	$ 2,355		$ 10,297
Payments for restructuring					$ 12,500
Restructuring reserve					$ 2,200	2,200
Operating Income (Loss) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 466	$ 2,000	$ 9,273	$ 3,419		$ 15,158