Stockholders' Equity - Earnings per share (Details) - USD ($) $ / shares in Units, $ 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
Components of basic and diluted earnings per share
Net income attributable to Waddell & Reed Financial, Inc.	$ 15,936	$ 33,054	$ 33,948	$ 32,053	$ 46,468	$ 46,305	$ 44,478	$ 46,337	$ 114,992	$ 183,588	$ 141,279
Weighted average shares outstanding - basic and diluted									73,299,000	80,468,000	83,573,000
Earnings per share:
Earnings per share, basic and diluted (in dollars per share)									$ 1.57	$ 2.28	$ 1.69
Dividends
Dividends declared (in dollars per share)	$ 0.25								$ 1.00	$ 1.00	$ 1.63
Dividends payable to stockholders	$ 17,200				$ 19,200				$ 17,200	$ 19,200
Common stock repurchases
Shares repurchased in the open market or privately									9,164,564	6,963,269	1,842,337
Shares repurchased from employees to cover income tax withholdings									548,132	729,882	402,337