Supplemental Disclosure for Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Supplemental disclosures of cash flow information:
Interest paid	$ 96,332	$ 103,006
Net income taxes (refunded) paid	(569)	1,153
Supplemental schedule of noncash investing and financing activities:
Transfer of loans and loans held for sale to OREO	4,736	10,226
Transfer of available for sale debt securities to held to maturity debt securities	1,017,275	0
Cash and cash equivalents	3,523,332	3,959,932	$ 4,082,826
Restricted cash in other assets	171,562	174,691
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 3,694,894	$ 4,134,623	$ 4,270,950	$ 3,419,488