Regulatory Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Parent Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 1,553,697	$ 1,458,344
Common Equity Tier One Capital Ratio	11.76%	11.44%
Common Equity Tier One Capital Required for Capital Adequacy	$ 594,373	$ 573,723
Total capital (to risk-weighted assets), Amount
Total Capital, Actual	1,747,611	1,649,664
Total Capital, Required For Capital Adequacy Purposes	1,056,664	1,019,952
Tier I capital (to risk-weighted assets), Amount
Tier I Capital, Actual (Risk Based)	1,652,831	1,556,371
Tier One Risk Based Capital Required for Capital Adequacy	792,498	764,964
Tier I capital (to average assets), Amount
Tier I Capital, Actual (Leverage)	1,652,831	1,556,371
Tier I Capital, Required For Capital Adequacy Purposes	$ 589,367	$ 590,176
Total capital and Tier I capital (to risk-weighted assets), Ratio
Total Capital (to Risk Weighted Assets), Actual	13.23%	12.94%
Total Capital (to Risk Weighted Assets), Minimum For Capital Adequacy Purposes	8.00%	8.00%
Tier I Capital (to Risk Weighted Assets), Actual (Risk Based)	12.51%	12.21%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Required for Capital Adequacy with Capital Buffer	$ 1,386,871	$ 1,259,004
Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets	10.50%	9.875%
Tier One Required for Capital Adequacy with Capital Buffer	$ 1,122,705	$ 1,004,015
Tier One Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets	8.50%	7.875%
Tier I capital (to average assets), Ratio
Tier I Capital (to Average Assets), Actual (Leverage)	11.22%	10.55%
Tier I Capital (to Average Assets), Minimum For Capital Adequacy Purposes (Leverage)	4.00%	4.00%
Subsidiaries [Member]
Total capital and Tier I capital (to risk-weighted assets), Ratio
Required for Capital Adequacy with Capital Buffer	$ 1,386,747	$ 1,258,951
Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets	10.50%	9.875%
Tier One Required for Capital Adequacy with Capital Buffer	$ 924,498	$ 812,740
Tier One Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets	8.50%	7.875%
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital	$ 1,811,862	$ 1,737,092
Common Equity Tier One Capital Ratio	13.72%	13.63%
Common Equity Tier One Capital Required for Capital Adequacy	$ 594,320	$ 573,699
Total capital (to risk-weighted assets), Amount
Total Capital, Actual	1,906,642	1,830,385
Total Capital, Required For Capital Adequacy Purposes	1,056,569	1,019,910
Required To Be Well Capitalized under Prompt Corrective Action Provisions	$ 1,320,711	$ 1,274,887
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier I capital (to risk-weighted assets), Amount
Tier I Capital, Actual (Risk Based)	$ 1,811,862	$ 1,737,092
Tier One Risk Based Capital Required for Capital Adequacy	792,427	764,932
Tier I Capital, Minimum to be Well Capitalized Under Prompt Corrective Action Provisions (Risk Based)	1,056,569	1,019,910
Tier I capital (to average assets), Amount
Tier I Capital, Actual (Leverage)	1,811,862	1,737,092
Tier I Capital, Required For Capital Adequacy Purposes	589,604	590,639
Tier I Capital, Minimum to be Well Capitalized Under Prompt Corrective Action Provisions (Leverage)	$ 737,005	$ 738,299
Total capital and Tier I capital (to risk-weighted assets), Ratio
Total Capital (to Risk Weighted Assets), Actual	14.44%	14.36%
Total Capital (to Risk Weighted Assets), Minimum For Capital Adequacy Purposes	8.00%	8.00%
Tier I Capital (to Risk Weighted Assets), Actual (Risk Based)	13.72%	13.63%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Tier I Capital (to Risk Weighted Assets), Minimum to be Well Capitalized Under Prompt Corrective Action Provisions (Risk Based)	8.00%	8.00%
Common Equity Tier One Capital Required to be Well-Capitalized	$ 858,462	$ 828,677
Tier I capital (to average assets), Ratio
Tier I Capital (to Average Assets), Actual (Leverage)	12.29%	11.76%
Tier I Capital (to Average Assets), Minimum For Capital Adequacy Purposes (Leverage)	4.00%	4.00%
Tier I Capital (to Average Assets), Minimum to be Well Capitalized Under Prompt Corrective Action Provisions (Leverage)	5.00%	5.00%
Common equity tier 1 capital [Member] | Parent Company
Total capital and Tier I capital (to risk-weighted assets), Ratio
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Common equity tier 1 capital [Member] | Bank
Total capital and Tier I capital (to risk-weighted assets), Ratio
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Tier I Capital (to Risk Weighted Assets), Minimum to be Well Capitalized Under Prompt Corrective Action Provisions (Risk Based)	6.50%	6.50%
Common Equity Tier 1 [Member] | Parent Company
Total capital and Tier I capital (to risk-weighted assets), Ratio
Tier One Required for Capital Adequacy with Capital Buffer	$ 924,581	$ 812,774
Tier One Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets	7.00%	6.375%
Common Equity Tier 1 [Member] | Subsidiaries [Member]
Total capital and Tier I capital (to risk-weighted assets), Ratio
Tier One Required for Capital Adequacy with Capital Buffer	$ 924,498	$ 812,740
Tier One Required for Capital Adequacy with Capital Buffer to Risk Weighted Assets	7.00%	6.375%