Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Changes in the carrying amount of goodwill
Balance at the beginning of year	$ 143,874	$ 140,341
Additions	3,638	3,533
Balance at end of period	$ 147,512	$ 143,874