Goodwill and Other Intangible Assets - Components of Goodwill (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 73,095	$ 73,095
Accumulated impairment	(42,231)	(42,231)
Goodwill	$ 30,864	$ 30,864	$ 67,530