Schedule of Reverse Repurchase Agreements by Maturity (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2014		Dec. 31, 2013
Reverse Repurchase Agreements [Line Items]
Reverse repurchase agreements	$ 1,188,831	[1]	$ 1,236,166	[1]
Debt, Weighted Average Interest Rate	0.74%		0.90%
Remaining Days to Maturity, Reverse Repurchase Agreements	62 days		56 days
Maturity up to 30 days [Member]
Reverse Repurchase Agreements [Line Items]
Reverse repurchase agreements	368,522		369,861
Debt, Weighted Average Interest Rate	0.66%		0.53%
Remaining Days to Maturity, Reverse Repurchase Agreements	16 days		14 days
Maturity 31 to 60 days [Member]
Reverse Repurchase Agreements [Line Items]
Reverse repurchase agreements	348,115		402,206
Debt, Weighted Average Interest Rate	0.68%		1.12%
Remaining Days to Maturity, Reverse Repurchase Agreements	45 days		45 days
Maturity 61 to 90 days [Member]
Reverse Repurchase Agreements [Line Items]
Reverse repurchase agreements	292,692		320,161
Debt, Weighted Average Interest Rate	0.46%		0.78%
Remaining Days to Maturity, Reverse Repurchase Agreements	74 days		72 days
Maturity 91 to 120 days [Member]
Reverse Repurchase Agreements [Line Items]
Reverse repurchase agreements	3,828		8,233
Debt, Weighted Average Interest Rate	0.38%		1.40%
Remaining Days to Maturity, Reverse Repurchase Agreements	106 days		100 days
Maturity 121 to 150 days [Member]
Reverse Repurchase Agreements [Line Items]
Reverse repurchase agreements	28,875		38,856
Debt, Weighted Average Interest Rate	0.35%		0.49%
Remaining Days to Maturity, Reverse Repurchase Agreements	136 days		135 days
Maturity 151 to 180 days [Member]
Reverse Repurchase Agreements [Line Items]
Reverse repurchase agreements	$ 146,799		$ 96,849
Debt, Weighted Average Interest Rate	1.70%		1.90%
Remaining Days to Maturity, Reverse Repurchase Agreements	174 days		179 days

[1] In the Company's Consolidated Statement of Assets, Liabilities, and Equity, all balances associated with repurchase agreements, reverse repurchase agreements, and financial derivatives are presented on a gross basis.