Significant Accounting Policies - Graduation Fund (Details)	6 Months Ended
	Jun. 30, 2016 USD ($) item	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Schedule of activity in the Graduation Fund
Consecutive terms of non attendance in which Graduation Fund credits will be lost | item	1
Number of free courses | item	1
Number of successfully completed courses | item	3
Expected collection period of tuition receivable	12 months
Balance at beginning of year	$ 20,937,000	$ 9,706,000
Revenue deferred	12,063,000	7,753,000
Benefit redeemed	(7,741,000)	(1,845,000)
Balance at end of year	25,259,000	$ 15,614,000
Current Liability [Member]
Schedule of activity in the Graduation Fund
Graduation fund estimated to be redeemed	14,700,000
Other Assets [Member]
Restricted cash
Restricted cash	0		$ 0
Minimum protective endowment	$ 500,000