Derivative Financial Instruments - Summary of Outstanding Swaps (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Assets, at Fair Value	$ 10,613,000		$ 10,365,000
Liabilities, at Fair Value	2,712,000		1,982,000
Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 950,000,000
Average Fixed Pay Rate	1.40%
Average Receive Rate	1.20%
Assets, at Fair Value	$ 5,811,000
Average Maturity	3 years 2 months 22 days	3 years 4 months 10 days
Swap [Member] | 1-3 Years
Derivatives, Fair Value [Line Items]
Notional Amount	$ 650,000,000
Average Fixed Pay Rate	1.09%
Average Receive Rate	1.18%
Assets, at Fair Value	$ 8,485,000
Average Maturity	2 years 6 months 20 days
Swap [Member] | 3-5 Years
Derivatives, Fair Value [Line Items]
Notional Amount	$ 300,000,000		$ 700,000,000
Average Fixed Pay Rate	2.08%		1200.00%
Average Receive Rate	1.24%		910.00%
Assets, at Fair Value			$ 9,500,000
Liabilities, at Fair Value	$ (2,674,000)
Average Maturity	4 years 8 months 8 days