Restructuring Expenses - Other Restructuring Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended			36 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Restructuring activities
Restructuring expenses	$ 224	$ 8	$ 343	$ 687	$ 1,524	$ 1,826	$ 2,128	$ (3,272)	$ 1,262	$ 2,206	$ 50,925
Other Restructuring
Restructuring activities
Liability, beginning of the period				$ 1,450				$ 869	1,450	869	8,441	$ 8,441
Cash payments									(1,794)	(3,374)	(10,570)
Restructuring expenses									344	3,955	2,998
Liability, end of the period	$ 0				$ 1,450				$ 0	$ 1,450	$ 869	$ 0