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Stockholders' Equity and Employee Benefit Plans (Employee Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity and Employee Benefit Plans Disclosure [Abstract]
Employee contribution benefit plan expense	$ 6.2	$ 5.4	$ 1.4
Allowable purchase interval duration	6 months
Price per share to fair market value	85.00%

X

- Definition

Employee Stock Ownership Plan (ESOP), Allowable Purchase Interval Duration

+ References

No definition available.

+ Details

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X

- Definition

Employee Stock Ownership Plan, Share Price to Fair Market Value

+ References

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+ Details

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X

- Definition

Stockholders' Equity and Employee Benefit Plans Disclosure [Abstract]

+ References

No definition available.

+ Details

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- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

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