Fair Value of Financial Instruments (Details 1) - Fair Value Non-recurring - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets and liabilities measured at fair value on a non-recurring basis
Goodwill	$ 47,842	$ 47,842
Property, equipment and software, net	22,540	20,856
Pre-publication costs, net	16,441	15,070
Other intangible assets, net	3,231	4,499
Curriculum and Technology
Assets and liabilities measured at fair value on a non-recurring basis
Acquired intangible assets, net	2,731	5,209
Publishing Rights
Assets and liabilities measured at fair value on a non-recurring basis
Acquired intangible assets, net	1,459	2,762
Significant Unobservable Inputs (Level 3)
Assets and liabilities measured at fair value on a non-recurring basis
Goodwill	47,842	47,842
Property, equipment and software, net	22,540	20,856
Pre-publication costs, net	16,441	15,070
Other intangible assets, net	3,231	4,499
Significant Unobservable Inputs (Level 3) | Curriculum and Technology
Assets and liabilities measured at fair value on a non-recurring basis
Acquired intangible assets, net	2,731	5,209
Significant Unobservable Inputs (Level 3) | Publishing Rights
Assets and liabilities measured at fair value on a non-recurring basis
Acquired intangible assets, net	$ 1,459	$ 2,762