Fair Value Measurements Nonrecurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Fair value measurements at reporting date using:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	$ 6,988,207		$ 6,988,207		$ 6,734,216
Fair value measurements at reporting date using: | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	0		0		0
Fair value measurements at reporting date using: | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	0		0		0
Fair value measurements at reporting date using: | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	6,988,207		6,988,207		$ 6,734,216
Fair value measurements at reporting date using: | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	1,144	$ 3,051	1,144	$ 3,051
Fair value measurements at reporting date using: | Fair Value, Measurements, Nonrecurring | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	0	0	0	0
Fair value measurements at reporting date using: | Fair Value, Measurements, Nonrecurring | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	0	0	0	0
Fair value measurements at reporting date using: | Fair Value, Measurements, Nonrecurring | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets: Impaired loans	1,144	3,051	1,144	3,051
Gain (losses) from fair value changes | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (losses) from fair value changes	$ 220	$ (711)	$ 592	$ (927)