Subsequent Events Subsequent Events (Details) - shares	Mar. 31, 2019	Dec. 31, 2017
Subsequent Event [Line Items]
Share repurchase program, number of shares authorized	800,000	800,000

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

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