Goodwill - Changes in Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Goodwill [Roll Forward]
Balance at beginning of period		$ 217,094
Acquisitions		17,573
Balance at end of period	$ 234,667	234,667
Title
Goodwill [Roll Forward]
Balance at beginning of period		211,365
Acquisitions	17,600	17,573
Balance at end of period	228,938	228,938
Ancillary Services and Corporate
Goodwill [Roll Forward]
Balance at beginning of period		5,729
Acquisitions		0
Balance at end of period	$ 5,729	$ 5,729