Goodwill Changes in the Carrying Value of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Goodwill Roll Forward
Net carrying value at beginning of period	$ 140,638	$ 130,843	$ 140,638	$ 129,706
Acquisitions	0	0	0	1,137
Net carrying value at end of period	$ 140,638	$ 130,843	$ 140,638	$ 130,843