Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

Debt - Private Placement Shelf Agreement (Details) - Maximum - Senior Notes - USD ($) $ in Thousands	Aug. 02, 2017	Sep. 22, 2016
Prudential Private Placement Shelf Agreement
Debt Instrument [Line Items]
Agreement face amount	$ 100,000
MetLife Private Placement Shelf Agreement
Debt Instrument [Line Items]
Agreement face amount		$ 100,000