Business Acquisitions and Divestitures (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair values of net assets acquired:
Goodwill			$ 11,810	$ 13,036	$ 13,686
Associate Migrations [Member]
Fair values of net assets acquired:
Equipment		$ 10
Intangible assets, primarily non-compete agreements		171
Working capital, including work in progress		666
Goodwill		695
Fair value of net assets acquired		1,542
Fair value of purchase price		$ 1,542
Business Strategy, Inc. [Member]
Fair values of net assets acquired:
Equipment	$ 70
Intangible assets, primarily non-compete agreements	4,041
Working capital, including work in progress	1,967
Deferred tax liabilities	(1,736)
Goodwill	7,577
Fair value of net assets acquired	11,919
Fair value of purchase price	$ 11,919