Restructuring Charges (Restructuring Reserve) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring Reserve [Roll Forward]
Beginning balance	$ 7,261	$ 4,968	$ 4,049	$ 6,617
Accruals for voluntary and involuntary termination benefits	(24)	(25)	6,428	6
Payments	(2,604)	(555)	(5,844)	(2,235)
Ending balance	4,633	4,388	4,633	4,388
Severance Charges
Restructuring Reserve [Roll Forward]
Beginning balance	3,731	593	81	1,930
Accruals for voluntary and involuntary termination benefits	(24)	0	6,428	0
Payments	(2,502)	(365)	(5,304)	(1,702)
Ending balance	1,205	228	1,205	228
Lease Termination Charges
Restructuring Reserve [Roll Forward]
Beginning balance	3,530	4,375	3,968	4,687
Accruals for voluntary and involuntary termination benefits	0	(25)	0	6
Payments	(102)	(190)	(540)	(533)
Ending balance	$ 3,428	$ 4,160	$ 3,428	$ 4,160