Condensed Financial Information - Parent Company Only Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets [Abstract]
Other assets	$ 855,470	$ 612,883
Investments in:
Total Assets	21,886,040	20,682,152
Other liabilities	376,107	300,835
Total Liabilities	19,543,864	18,434,579
Shareholders' Equity [Abstract]
Shareholders’ equity	2,342,176	2,247,573	$ 2,229,857	$ 2,121,115
Total Liabilities and Shareholders’ Equity	21,886,040	20,682,152
Parent
Assets [Abstract]
Cash and cash equivalents	10,841	30,941	$ 22,857	$ 8,568
Other assets	1,087	7,072
Receivable from subsidiaries	78,025	51,646
Investments in:
Bank subsidiary (1)	2,555,448	2,451,651
Non-bank subsidiaries	419,145	425,670
Total Assets	3,064,546	2,966,980
Long-term debt	387,756	386,913
Payable to non-bank subsidiaries	276,768	247,801
Other liabilities	57,846	84,693
Total Liabilities	722,370	719,407
Shareholders' Equity [Abstract]
Shareholders’ equity	2,342,176	2,247,573
Total Liabilities and Shareholders’ Equity	$ 3,064,546	$ 2,966,980