Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Exercise of options, income tax expense	$ 0	$ 0	$ 2,051
Restricted share grants, settled (in shares)	58	92	137

Number of shares related to Restricted Stock Award forfeited during the period.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration