Borrowings and Subordinated Debentures - Subordinated Debentures (Details)	6 Months Ended
	Jun. 30, 2017 USD ($) trust	Dec. 31, 2016 USD ($)
Borrowings and Subordinated Debentures
Junior subordinated debenture owed to unconsolidated subsidiary trust	$ 25,774,000	$ 25,774,000
Number of Delaware trust affiliates | trust	2
Royal Bancshares Capital Trust I | Common Stock
Borrowings and Subordinated Debentures
Aggregate principal amount, common securities	$ 387,000
Royal Bancshares Capital Trust I | Trust Preferred Securities
Borrowings and Subordinated Debentures
Aggregate principal amount, capital securities	12,500,000
Trust I
Borrowings and Subordinated Debentures
Junior subordinated debenture owed to unconsolidated subsidiary trust	$ 12,900,000
Interest rate on notes payable (as a percent)	3.40%
Trust I | London Interbank Offered Rate (LIBOR) [Member]
Borrowings and Subordinated Debentures
Description of variable rate basis on notes payable	3-month LIBOR
Trust preferred securities basis spread on variable rate (as a percent)	2.15%
Trust II
Borrowings and Subordinated Debentures
Junior subordinated debenture owed to unconsolidated subsidiary trust	$ 12,900,000
Interest rate on notes payable (as a percent)	3.40%
Trust II | London Interbank Offered Rate (LIBOR) [Member]
Borrowings and Subordinated Debentures
Description of variable rate basis on notes payable	3-month LIBOR