Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Changes in the carrying amount of goodwill
Balance at the beginning of period	$ 140,341	$ 114,588	$ 114,588
Additions	3,333		26,480
Impairment adjustment		$ (727)	(727)
Balance at the end of period	$ 143,674		$ 140,341