Note 22 - Regulatory Matters (Details) - Capital and Leverage Ratios - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equtiy Tier 1 capital ( to risk-weighted assets)		$ 1,383,377
Common equtiy Tier 1 capital ( to risk-weighted assets)		12.95%
Common equtiy Tier 1 capital minimum requirement		$ 480,830
Common equtiy Tier 1 capital minimum requirement		4.50%
Excess		$ 902,547
Excess		8.45%
Tier 1 capital (to risk-weighted assets)		$ 1,498,810	$ 1,406,511
Tier 1 capital (to risk-weighted assets)		14.03%	14.96%
Tier 1 capital minimum requirement		$ 641,107	$ 376,072
Tier 1 capital minimum requirement		6.00%	4.00%
Excess		$ 857,703	$ 1,030,439
Excess		8.03%	10.96%
Total capital (to risk-weighted assets)		$ 1,634,631	$ 1,524,702
Total capital (to risk-weighted assets)		15.30%	16.22%
Total capital minimum requirement		$ 854,809	$ 752,144
Total capital minimum requirement		8.00%	8.00%
Excess		$ 779,822	$ 772,558
Excess		7.30%	8.22%
Tier 1 capital (to average assets)
– Leverage ratio		$ 1,498,810	$ 1,406,511
– Leverage ratio		11.95%	12.99%
Minimum leverage requirement		$ 501,875	$ 433,121
Minimum leverage requirement		4.00%	4.00%
Excess		$ 996,935	$ 973,390
Excess		7.95%	8.99%
Risk-weighted assets		$ 10,685,115	$ 9,401,803
Total average assets (1)	[1]	12,546,879	10,828,015
Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equtiy Tier 1 capital ( to risk-weighted assets)		$ 1,443,159
Common equtiy Tier 1 capital ( to risk-weighted assets)		13.54%
Common equtiy Tier 1 capital minimum requirement		$ 479,801
Common equtiy Tier 1 capital minimum requirement		4.50%
Excess		$ 963,358
Excess		9.04%
Tier 1 capital (to risk-weighted assets)		$ 1,443,159	$ 1,353,481
Tier 1 capital (to risk-weighted assets)		13.54%	14.42%
Tier 1 capital minimum requirement		$ 639,735	$ 375,318
Tier 1 capital minimum requirement		6.00%	4.00%
Excess		$ 803,424	$ 978,163
Excess		7.54%	10.42%
Total capital (to risk-weighted assets)		$ 1,576,525	$ 1,471,337
Total capital (to risk-weighted assets)		14.79%	15.68%
Total capital minimum requirement		$ 852,980	$ 750,637
Total capital minimum requirement		8.00%	8.00%
Excess		$ 723,545	$ 720,700
Excess		6.79%	7.68%
Tier 1 capital (to average assets)
– Leverage ratio		$ 1,443,159	$ 1,353,481
– Leverage ratio		11.53%	12.52%
Minimum leverage requirement		$ 500,455	$ 432,350
Minimum leverage requirement		4.00%	4.00%
Excess		$ 942,704	$ 921,131
Excess		7.53%	8.52%
Risk-weighted assets		$ 10,662,248	$ 9,382,961
Total average assets (1)	[1]	$ 12,511,382	$ 10,808,747

[1] The quarterly total average assets reflect all debt securities at amortized cost, equity security with readily determinable fair values at the lower of cost or fair value, and equity securities without readily determinable fair values at historical cost.