Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 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		3,228		26,480
Impairment adjustment	$ (727)		$ (727)	(727)
Balance at the end of period		$ 143,569		$ 140,341