Subsequent Events (Details) - $ / shares		3 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	[1]		$ 1.050	$ 1.050	$ 1.050
Common Stock [Member]
Subsequent Event [Line Items]
Dividends Payable, Date to be Paid	[1]		Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018
Dividends Payable, Date of Record	[1]		Sep. 14, 2018	Jun. 15, 2018	Mar. 16, 2018
Dividends Payable, Date Declared	[1]		Aug. 02, 2018	May 17, 2018	Feb. 21, 2018
Paid subsequent to year end [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Cash Paid		$ 1.125
Dividend Declared [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Dividends Payable, Date to be Paid		Dec. 31, 2018
Dividends Payable, Date of Record		Dec. 14, 2018
Dividends Payable, Date Declared		Oct. 15, 2018

[1] Inclusive of dividends accrued for holders of unvested restricted stock units, which will be paid when and if the restricted stock units vest.