Business Combinations (Purchase Price Allocation) (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015	Oct. 02, 2015
Business Acquisition [Line Items]
Goodwill		$ 438,450	$ 436,449
Smart Tuition [Member]
Business Acquisition [Line Items]
Net working capital, excluding deferred revenue				$ 202
Property and equipment				2,457
Deferred revenue				(6,500)
Deferred tax asset				2,637
Intangible assets				97,800
Goodwill				90,376
Total purchase price	[1]			$ 186,972

[1] (1) The purchase price differs from the net cash outlay of $187.3 million due to certain insignificant acquisition-related expenses included therein.