Equity Transactions (Details) $ / shares in Units, $ in Thousands				3 Months Ended				12 Months Ended			87 Months Ended
	Feb. 21, 2019 $ / shares	Feb. 15, 2019 USD ($)	Feb. 01, 2017 USD ($) day $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Sep. 30, 2018 $ / shares	Jun. 30, 2018 $ / shares	Mar. 31, 2018 $ / shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares shares	Feb. 01, 2020 $ / shares shares	Feb. 24, 2017 $ / shares
Equity, Class of Treasury Stock [Line Items]
Common stock authorized to be repurchased (in shares)				4,200,000				4,200,000
Remaining common stock authorized for repurchase (in shares)									624,803		624,803
Repurchase of common shares (in shares)								258,953			3,555,242
Cost of shares repurchased | $								$ 27,500			$ 379,200
Weighted average price (in $ per share) | $ / shares											$ 106.65
Stock issued (in shares)								1,260,169
Cash dividends declared per common share (in $ per share) | $ / shares				$ 0.55	$ 0.55	$ 0.45	$ 0.45	$ 2	$ 1.80	$ 1.8
Cash dividends declared, common | $								$ 15,267	$ 13,545	$ 13,015
Cash dividends declared per preferred share (in $ per share) | $ / shares				$ 1.8125	$ 1.8125	$ 1.8125	$ 1.8125	$ 7.25	$ 7.25	$ 0
Cash dividends declared. preferred | $								$ 8,337	$ 8,337
Dividends payable | $				$ 7,762				$ 7,762	$ 6,528		$ 6,528
Convertible preferred stock
Equity, Class of Treasury Stock [Line Items]
Stock issued (in shares)			1,150,000
Preferred stock dividend rate			7.25%
Preferred stock liquidation preference (in $ per share) | $ / shares			$ 100.00										$ 100
Preferred stock conversion, threshold consecutive trading days | day			20
Convertible preferred stock | Forecast | Minimum
Equity, Class of Treasury Stock [Line Items]
Preferred stock, shares issuable upon conversion (in shares)												0.7583
Conversion price of stock (USD per share) | $ / shares												$ 109.90
Convertible preferred stock | Forecast | Maximum
Equity, Class of Treasury Stock [Line Items]
Preferred stock, shares issuable upon conversion (in shares)												0.9100
Conversion price of stock (USD per share) | $ / shares												$ 131.88
Common Stock
Equity, Class of Treasury Stock [Line Items]
Net proceeds from stock issuance | $			$ 111,000
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Cash dividends declared per common share (in $ per share) | $ / shares	$ 0.55
Cash dividends declared, common | $		$ 5,700
Cash dividends declared per preferred share (in $ per share) | $ / shares	$ 1.8125
Cash dividends declared. preferred | $		$ 2,100
Public Offering
Equity, Class of Treasury Stock [Line Items]
Stock issued (in shares)								1,046,500
Proceeds received on sale of stock | $								$ 109,500
RidgeWorth
Equity, Class of Treasury Stock [Line Items]
Stock issued (in shares)								213,669