Summary of Significant Accounting Policies - Revenue - Contract Fulfillment Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Capitalized commissions asset
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Carrying Amount	$ 27,562	$ 23,787
Accumulated Amortization	(24,923)	(34,637)
Gross Carrying Amount	52,485	58,424
Intake Costs asset
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Carrying Amount	15,114	15,244
Accumulated Amortization	(21,041)	(24,504)
Gross Carrying Amount	$ 36,155	$ 39,748

Amount, before allowance for credit loss, of right to consideration in exchange for good or service transferred to customer, when right is conditioned on something other than passage of time.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130533-203044

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Balance Type:	debit
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