Acquisition of New York Code and Design Academy - Purchase Price Allocation (Details) - USD ($)		1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 13, 2016	Aug. 31, 2016	Apr. 30, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill				$ 20,744,000	$ 20,744,000	$ 20,744,000		$ 6,800,000
Cash paid for acquisition, net of cash acquired						7,635,000
New York Code And Design Academy, Inc.
Business Acquisition [Line Items]
Cash				790,000		790,000
Other assets				1,265,000		1,265,000
Trade name				5,660,000		5,660,000
Goodwill				13,944,000		13,944,000
Liabilities assumed				(4,734,000)		(4,734,000)
Total assets acquired and liabilities assumed, net				16,925,000		16,925,000
Less: contingent consideration				(14,500,000)		(14,500,000)
Cash paid for acquisition, net of cash acquired						$ 1,635,000
Reduction in fair value of contingent consideration				$ 1,300,000	7,800,000
Contingent consideration payment	$ 4,600,000	$ 500,000	$ 6,000,000		0
Deferred payment arrangements value					0
New York Code And Design Academy, Inc. | Maximum
Business Acquisition [Line Items]
Contingent consideration					$ 11,500,000		$ 11,500,000