Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Stockholders' Equity (Narrative) (Details) - USD ($)		3 Months Ended		9 Months Ended
Stockholders' Equity (Narrative) (Details) - USD ($)	Jan. 23, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock Repurchased During Period, Shares	4,400,000
Stock Repurchase Program, Authorized Amount	$ 150,000,000
Stock Repurchase, Weighted Average Price of Shares Repurchased during period				$ 34.39
Common Stock [Member]
Stock Repurchased During Period, Shares		236,990	2,431,649	4,362,067	3,777,107