Common Stock (Common Stock Repurchase Program) (Details) $ in Thousands	12 Months Ended		60 Months Ended		252 Months Ended
	Dec. 31, 2019 shares		Dec. 31, 2019 shares		Dec. 31, 2019 USD ($) shares
Equity, Class of Treasury Stock [Line Items]
Shares repurchased	0				25,406,184	[1],[2],[3]
Cost, including commission | $					$ 423,647	[3]
Total remaining shares available for repurchase at December 31, 2019	393,816	[4]	393,816	[4]	393,816	[4]
Treasury shares acquired outside of repurchase programs					86,735
Stock Issued During Period, Shares, Treasury Stock Reissued	51,305		396,657

[1] Beginning in 2015, shares of the Company's common stock issued for employee benefit and stock incentive plans have been issued from the shares repurchased and held in treasury stock. The Company has issued 396,657 treasury shares since 2015 including 51,305 shares during 2019.

[2] Shares repurchased does not include 86,735 treasury shares related to employee compensation arrangements that were not part of the Company's repurchase program.

[3] Represents repurchased shares and cost since inception of the stock repurchase program in 1999.

[4] The Company may make purchases of shares of its common stock pursuant to its authorized program in open market transactions at prevailing prices and may engage in private transactions where appropriate. The repurchased shares will be available for issuance under employee benefit and stock incentive plans or the repurchased shares may be retired.