Condensed Financial Statements of BankUnited, Inc. (Schedule of Condensed Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	$ 89,456	$ 76,219	$ 81,451	$ 65,972	$ 52,403	$ 97,328	$ 89,900	$ 85,235	$ 313,098	$ 324,866	$ 614,273
Adjustments to reconcile net income to net cash provided by operating activities:
Equity based compensation									23,367	23,137	22,692
Net cash provided by operating activities									635,706	824,252	318,626
Cash flows from investing activities:
Purchase of investment securities available for sale									(3,896,234)	(4,138,994)	(3,131,798)
Proceeds from repayments and calls of investment securities									1,370,584	1,533,951	1,260,444
Other									(39,879)	(3,184)	(15,572)
Net cash used in investing activities									(1,075,496)	(2,041,531)	(2,452,576)
Cash flows from financing activities:
Dividends paid									(84,083)	(91,305)	(91,628)
Exercise of stock options									(5,817)	(7,727)	(62,095)
Other									25,682	7,424	8,837
Net cash provided by financing activities									272,390	1,404,770	1,880,219
Net (decrease) increase in cash and cash equivalents									(167,400)	187,491	(253,731)
Cash and cash equivalents, beginning of period				382,073				194,582	382,073	194,582	448,313
Cash and cash equivalents, end of period	214,673				382,073				214,673	382,073	194,582
Supplemental schedule of non-cash investing and financing activities:
Dividends declared, not paid									20,775	21,673	23,055
Payments for Repurchase of Common Stock									(154,030)	(299,972)	0
Parent Company [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income									313,098	324,866	614,273
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries									(30,723)	70,064	(519,250)
Equity based compensation									23,367	23,137	22,692
Increase (Decrease) in Other Operating Assets and Liabilities, Net									(8,656)	(15,654)	3,343
Net cash provided by operating activities									297,086	402,413	121,058
Cash flows from investing activities:
Capital contributions to subsidiary									0	0	(55,000)
Purchase of investment securities available for sale									(8,963)	0	0
Proceeds from repayments and calls of investment securities									11,575	0	15,000
Other									(142)	(156)	(250)
Net cash used in investing activities									2,470	(156)	(40,250)
Cash flows from financing activities:
Dividends paid									(84,083)	(91,305)	(91,628)
Exercise of stock options									(5,817)	(7,727)	(62,095)
Other									6,514	6,560	7,297
Net cash provided by financing activities									(238,810)	(390,110)	(36,830)
Net (decrease) increase in cash and cash equivalents									60,746	12,147	43,978
Cash and cash equivalents, beginning of period				$ 143,843				$ 131,696	143,843	131,696	87,718
Cash and cash equivalents, end of period	$ 204,589				$ 143,843				204,589	143,843	131,696
Supplemental schedule of non-cash investing and financing activities:
Dividends declared, not paid									20,775	21,673	23,055
Payments for Repurchase of Common Stock									$ (154,030)	$ (299,972)	$ 0