Borrowings and Subordinated Debentures (Details 2) $ in Thousands, € in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2020 EUR (€)	Dec. 31, 2019 USD ($)
Subordinated Borrowing [Line Items]
Subordinated Debentures, Gross	$ 540,220		$ 540,690
Subordinated debentures	$ 458,994		$ 458,209
Rate	0.45%	0.45%	1.64%
Trust Preferred Securities Two Thousand Six Series Three
Subordinated Borrowing [Line Items]
Denomination value | €		€ 25.8
London Interbank Offered Rate (LIBOR) | Subordinated Debt Trust V Due September 2033
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	3.10%
London Interbank Offered Rate (LIBOR) | Subordinated Debt Trust VI Due September 2033
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	3.05%
London Interbank Offered Rate (LIBOR) | Subordinated Debt Trust CII Due September 2033
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	2.95%
London Interbank Offered Rate (LIBOR) | Subordinated Debt Trust VII Due April 2034
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	2.75%
London Interbank Offered Rate (LIBOR) | Subordinated Debt Trust CIII Due September 2035
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.69%
London Interbank Offered Rate (LIBOR) | Subordinated Debt Trust FCCI Due March 2037
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.60%
London Interbank Offered Rate (LIBOR) | Subordinated Debt Trust FCBI Due December 2035
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.55%
London Interbank Offered Rate (LIBOR) | Trust Preferred Securities Two Thousand Five Series One
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.95%
London Interbank Offered Rate (LIBOR) | Trust Preferred Securities Two Thousand Five Series Two
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.95%
London Interbank Offered Rate (LIBOR) | Two Thousand Six One Term Debt Securitization
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.95%
London Interbank Offered Rate (LIBOR) | Two Thousand Six Two Term Debt Securitization
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.95%
London Interbank Offered Rate (LIBOR) | Trust Preferred Securities Two Thousand Six Series Four
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.95%
London Interbank Offered Rate (LIBOR) | Trust Preferred Securities Two Thousand Six Series Five
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.95%
London Interbank Offered Rate (LIBOR) | Two Thousand Seven One Term Debt Securitization
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	1.95%
Euribor Rate | Trust Preferred Securities Two Thousand Six Series Three
Subordinated Borrowing [Line Items]
Rate Index (Quarterly Reset)	2.05%
Subordinated Debentures
Subordinated Borrowing [Line Items]
Unamortized discount	$ (81,226)		$ (82,481)
Rate	3.43%	3.43%	3.87%
Subordinated Debentures | Subordinated Debt Trust V Due September 2033
Subordinated Borrowing [Line Items]
Balance	$ 10,310		$ 10,310
Rate	3.94%	3.94%	5.00%
Date Issued	Aug. 15, 2003
Maturity Date	Sep. 17, 2033
Description of variable rate basis	3-month LIBOR + 3.10
Subordinated Debentures | Subordinated Debt Trust VI Due September 2033
Subordinated Borrowing [Line Items]
Balance	$ 10,310		$ 10,310
Rate	3.79%	3.79%	4.94%
Date Issued	Sep. 03, 2003
Maturity Date	Sep. 15, 2033
Description of variable rate basis	3-month LIBOR + 3.05
Subordinated Debentures | Subordinated Debt Trust CII Due September 2033
Subordinated Borrowing [Line Items]
Balance	$ 5,155		$ 5,155
Rate	3.79%	3.79%	4.85%
Date Issued	Sep. 17, 2003
Maturity Date	Sep. 17, 2033
Description of variable rate basis	3-month LIBOR + 2.95
Subordinated Debentures | Subordinated Debt Trust VII Due April 2034
Subordinated Borrowing [Line Items]
Balance	$ 61,856		$ 61,856
Rate	4.52%	4.52%	4.69%
Date Issued	Feb. 05, 2004
Maturity Date	Apr. 23, 2034
Description of variable rate basis	3-month LIBOR + 2.75
Subordinated Debentures | Subordinated Debt Trust CIII Due September 2035
Subordinated Borrowing [Line Items]
Balance	$ 20,619		$ 20,619
Rate	2.43%	2.43%	3.58%
Date Issued	Aug. 15, 2005
Maturity Date	Sep. 15, 2035
Description of variable rate basis	3-month LIBOR + 1.69
Subordinated Debentures | Subordinated Debt Trust FCCI Due March 2037
Subordinated Borrowing [Line Items]
Balance	$ 16,495		$ 16,495
Rate	2.34%	2.34%	3.49%
Date Issued	Jan. 25, 2007
Maturity Date	Mar. 15, 2037
Description of variable rate basis	3-month LIBOR + 1.60
Subordinated Debentures | Subordinated Debt Trust FCBI Due December 2035
Subordinated Borrowing [Line Items]
Balance	$ 10,310		$ 10,310
Rate	2.29%	2.29%	3.44%
Date Issued	Sep. 30, 2005
Maturity Date	Dec. 15, 2035
Description of variable rate basis	3-month LIBOR + 1.55
Subordinated Debentures | Trust Preferred Securities Two Thousand Five Series One
Subordinated Borrowing [Line Items]
Balance	$ 82,475		$ 82,475
Rate	2.69%	2.69%	3.85%
Date Issued	Nov. 21, 2005
Maturity Date	Dec. 15, 2035
Description of variable rate basis	3-month LIBOR + 1.95
Subordinated Debentures | Trust Preferred Securities Two Thousand Five Series Two
Subordinated Borrowing [Line Items]
Balance	$ 128,866		$ 128,866
Rate	3.72%	3.72%	3.89%
Date Issued	Dec. 14, 2005
Maturity Date	Jan. 30, 2036
Description of variable rate basis	3-month LIBOR + 1.95
Subordinated Debentures | Two Thousand Six One Term Debt Securitization
Subordinated Borrowing [Line Items]
Balance	$ 51,545		$ 51,545
Rate	3.72%	3.72%	3.89%
Date Issued	Feb. 22, 2006
Maturity Date	Apr. 30, 2036
Description of variable rate basis	3-month LIBOR + 1.95
Subordinated Debentures | Two Thousand Six Two Term Debt Securitization
Subordinated Borrowing [Line Items]
Balance	$ 51,550		$ 51,550
Rate	3.72%	3.72%	3.89%
Date Issued	Sep. 27, 2006
Maturity Date	Oct. 30, 2036
Description of variable rate basis	3-month LIBOR + 1.95
Subordinated Debentures | Trust Preferred Securities Two Thousand Six Series Three
Subordinated Borrowing [Line Items]
Balance	$ 28,432		$ 28,902
Rate	1.65%	1.65%	1.64%
Date Issued	Sep. 29, 2006
Maturity Date	Oct. 30, 2036
Description of variable rate basis	3-month EURIBOR + 2.05
Subordinated Debentures | Trust Preferred Securities Two Thousand Six Series Four
Subordinated Borrowing [Line Items]
Balance	$ 16,470		$ 16,470
Rate	3.72%	3.72%	3.89%
Date Issued	Dec. 05, 2006
Maturity Date	Jan. 30, 2037
Description of variable rate basis	3-month LIBOR + 1.95
Subordinated Debentures | Trust Preferred Securities Two Thousand Six Series Five
Subordinated Borrowing [Line Items]
Balance	$ 6,650		$ 6,650
Rate	3.72%	3.72%	3.89%
Date Issued	Dec. 19, 2006
Maturity Date	Jan. 30, 2037
Description of variable rate basis	3-month LIBOR + 1.95
Subordinated Debentures | Two Thousand Seven One Term Debt Securitization
Subordinated Borrowing [Line Items]
Balance	$ 39,177		$ 39,177
Rate	3.72%	3.72%	3.89%
Date Issued	Jun. 13, 2007
Maturity Date	Jul. 30, 2037
Description of variable rate basis	3-month LIBOR + 1.95