Stockholders' Equity - Treasury Stock (Details) - USD ($) $ in Thousands	12 Months Ended	13 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 11, 2017
Treasury Stock
Authorized amount of common stock repurchase (in dollars)					$ 100,000
Purchase of common stock	$ 11,309	$ 3,018	$ 13,035	$ 14,300

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Balance Type:	debit
Period Type:	duration