Summary of Significant Accounting Policies (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) Office subsidiary shares	Mar. 31, 2015 shares
Accounting Policies [Abstract]
Number of domestic field offices of parent company | Office	62
Number of subsidiaries with international offices | subsidiary	1
Percentage of net service revenue from international operations (less than)	2.00%	2.00%
Health insurance maximum risk of loss liability per employee insurance plan (up to)	$ 350,000
Health insurance maximum aggregate amount of risk of loss liability for employee insurance plans (up to)	$ 450,000
Common stock equivalents (in shares) | shares	149	199