Summary Of Significant Accounting Policies Schedule of Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Dec. 08, 2014
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share						$ 0.65
Special dividend (per share amount)	$ 4.50		$ 2.25
Dividends Treatment For Federal Tax Purposes, Percentage	100.00%		100.00%		100.00%
Dividends treatment for federal tax purposes.	$ 6.82	[1]	$ 4.75	[2]	$ 2.37
Dividend Declared [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share	$ 5.15		$ 2.90
non-special dividend [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share	$ 0.65		$ 0.65
Allocated to fiscal two thousand thirteen [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Special dividend (per share amount)	$ 4.41		$ 2.44
Capital Gains Income [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Treatment For Federal Tax Purposes, Percentage	100.00%		51.29%		3.55%
Dividends treatment for federal tax purposes.	$ 6.82		$ 2.44		$ 0.08
Ordinary Income [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Treatment For Federal Tax Purposes, Percentage	0.00%		48.71%		96.45%
Dividends treatment for federal tax purposes.	$ 0.00		$ 2.31		$ 2.29
Allocated to fiscal two thousand fourteen [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Special dividend (per share amount)	$ 0.74		$ 0.46

[1] (1) The fourth quarter 2014 dividend of $5.15 per common share consists of a $4.50 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $4.41 per common share was allocable to 2014 and approximately $0.74 per common share is allocable to 2015.

[2] (2) The fourth quarter 2013 dividend of $2.90 per common share consists of a $2.25 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $2.44 per common share was allocable to 2013 and approximately $0.46 per common share is allocable to 2014.