Repurchase Agreements (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security
Repurchase Agreements [Abstract]
Weighted average of remaining maturities days	38 days	46 days
Repurchase Agreement Characteristics, Remaining Maturities [Abstract]
Less than one month, repurchase agreements	$ 776,666	$ 429,573
One to three months, repurchase agreements	821,926	1,231,687
Greater than three months, repurchase agreements	0	5,277
Total repurchase agreements	$ 1,598,592	$ 1,666,537
Repurchase Agreement Characteristics, Weighted Average Rates [Abstract]
Less than one month, weighted average rate	2.51%	1.44%
One to three months, weighted average rate	2.56%	1.48%
Greater than three months, weighted average rate	0.00%	1.52%
Weighted average rate	2.54%	1.47%
Number of overnight or demand securities | Security	0	0