Borrowings and Other Short-Term Liabilities - Short/Long-term and Other Short-term Borrowings (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Long-term borrowings:
Amount	$ 426,035	$ 426,002
Weighted Average Rate	2.12%	2.11%
Total borrowings	$ 2,166,035	$ 2,461,002
Total short-term and long-term borrowings, Weighted Average Rate	2.48%	2.41%
FHLB advances: 2.55% - 2.59% fixed-rate notes \| Minimum
Long-term borrowings:
Stated interest rate	2.55%
FHLB advances: 2.55% - 2.59% fixed-rate notes \| Maximum
Long-term borrowings:
Stated interest rate	2.59%
FHLB Advances \| FHLB advances: 0.92% - 7.44% fixed-rate notes due 2017 to 2020
Long-term borrowings:
Amount	$ 410,087	$ 410,102
Weighted Average Rate	2.00%	2.00%
Advances payable from Federal Home Loan Banks	$ 410,000	$ 410,000
Purchase accounting premiums	$ 100	100
FHLB Advances \| FHLB advances: 0.92% - 7.44% fixed-rate notes due 2017 to 2020 \| Minimum
Long-term borrowings:
Stated interest rate	1.00%
FHLB Advances \| FHLB advances: 0.92% - 7.44% fixed-rate notes due 2017 to 2020 \| Maximum
Long-term borrowings:
Stated interest rate	2.72%
Subordinated debt obligations \| Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035
Long-term borrowings:
Amount	$ 11,610	$ 11,572
Weighted Average Rate	4.90%	4.85%
Advances payable	$ 15,000	$ 15,000
Purchase accounting discounts	$ 3,400	3,400
Subordinated debt obligations \| Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 \| Minimum
Long-term borrowings:
Spread on variable rate	1.45%
Subordinated debt obligations \| Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 \| Maximum
Long-term borrowings:
Spread on variable rate	2.85%
Subordinated debt obligations \| Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032
Long-term borrowings:
Amount	$ 4,338	$ 4,328
Weighted Average Rate	6.05%	5.65%
Spread on variable rate	3.25%
Advances payable	$ 5,000	$ 5,000
Purchase accounting discounts	700	700
Collateralized customer deposits
Short-term borrowings:
Amount	$ 413,199	$ 382,687
Weighted Average Rate	0.59%	0.75%
FHLB Advances \| FHLB advances: 2.55% - 2.59% fixed-rate notes
Short-term borrowings:
Amount	$ 1,740,000	$ 2,035,000
Weighted Average Rate	2.57%	2.47%

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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