Summary of Significant Accounting Policies (Implementation Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Expensed pursuit costs
Restructuring Cost and Reserve [Line Items]
System implementation costs and severance costs	$ 5,066	$ 1,016
General and administrative expense
Restructuring Cost and Reserve [Line Items]
System implementation costs and severance costs	$ 1,011	$ 4,001

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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