Stockholders' Equity - Earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of basic and diluted earnings per share
Net income attributable to Waddell & Reed Financial, Inc.		$ 46,468	$ 46,305	$ 44,478	$ 46,337	$ 29,765	$ 53,582	$ 24,061	$ 33,871	$ 183,588	$ 141,279	$ 156,695
Weighted average shares outstanding - basic and diluted										80,468,000	83,573,000	82,668,000
Earnings per share:
Earnings per share, basic and diluted (in dollars per share)										$ 2.28	$ 1.69	$ 1.90
Dividends
Dividends accrued (in dollars per share)	$ 0.25									$ 1.00	$ 1.63	$ 1.84
Dividends to be paid	$ 19,200	$ 19,200				$ 20,700				$ 19,200	$ 20,700
Common stock repurchases
Shares repurchased in the open market or privately										6,963,269	1,842,337	2,320,726
Shares repurchased from employees to cover income tax withholdings										729,882	402,337	423,726