Summary of Significant Accounting Policies (Undistributed Income and Dividend Program) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	0 Months Ended	1 Months Ended		3 Months Ended		6 Months Ended		0 Months Ended
	Oct. 31, 2012	Oct. 31, 2013	Feb. 28, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jul. 01, 2014 Subsequent Event [Member]
Dividends [Abstract]
Dividends declared per share of common stock	$ 0.20		$ 0.20	$ 0.3	$ 0.25	$ 0.6	$ 0.50	$ 0.30
Dividends declared per share of common stock, increased		$ 0.30	$ 0.25
Net income applicable to common shareholders				$ 96,436	$ 69,123	$ 170,746	$ 108,185
Less: Dividends declared				18,426	15,000	36,773	29,887
Undistributed earnings				78,010	54,123	133,973	78,298
Common stock undistributed earnings				76,009	53,172	130,543	76,648
Unvested restricted stock award undistributed earnings				$ 2,001	$ 951	$ 3,430	$ 1,650