Equity (Details 2) $ in Millions		12 Months Ended
		Dec. 31, 2016 USD ($) affiliate		Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($)
Components of accumulated other comprehensive income (loss)
Balance at beginning of the period		$ 41.9		$ 186.9
Net current period other comprehensive income (loss)		(25.3)		(145.0)		$ (121.3)
Balance at end of the period		16.6		41.9		186.9
Available-for-sale securities, Pretax
Unrealized gains (losses) on available-for-sale securities		18.1		(35.6)		28.1
Reclassification of gains into net earnings on available-for-sale securities	[1]	(2.1)		(163.5)		(179.1)
Net change in available-for-sale securities		16.0		(199.1)		(151.0)
Cash flow hedges, Pretax
Unrealized losses on cash flow hedges		0.1		0.4		0.2
Net change in cash flow hedges		0.1		0.1		0.5
Reclassification into net earnings upon liquidation of foreign entities, pretax	[2]	(0.5)		0.0		(41.9)
Current Period translation adjustments, pretax		(34.9)		(22.0)		14.0
Cumulative translation adjustments, Pretax		(35.4)		(22.0)		(27.9)
Other comprehensive loss		(19.3)		(221.0)		(178.4)
Available-for-sale securities, Net of Tax
Unrealized gains (losses) on available-for-sale securities		11.4		(21.8)		15.7
Reclassification of gains into net earnings on available-for-sale securities	[1]	(1.3)		(101.4)		(109.3)
Net change in available-for-sale securities		10.1		(123.2)		(93.6)
Cash flow hedges, Net of Tax
Proportional share of unconsolidated affiliates other comprehensive income		0.0		0.4		0.1
Net change in cash flow hedges		0.0		0.2		0.2
Reclassification into net earnings upon liquidation of foreign entities, net of tax		(0.5)	[2]	0.0	[2]	(41.9)
Current period translation adjustment, net of tax		(34.9)		(22.0)		14.0
Cumulative translation adjustments, Net of Tax		(35.4)		(22.0)		(27.9)
Other comprehensive loss		$ (25.3)		(145.0)		(121.3)
One of DST's unconsolidated affiliates
Cash flow hedges, Net of Tax
Number of unconsolidated affiliates with an interest rate swap | affiliate		1
Unconsolidated affiliate's interest rate swap liability, fair value		$ 33.1		44.7		50.2
Equity Method Investment, Ownership Percentage		50.00%
Proportionate share in unconsolidated affiliate's interest rate swap liability		$ 16.5		22.4		25.1
Foreign currency
Cash flow hedges, Pretax
Reclassification of losses into net earnings on cash flow hedges	[3]	0.0		(0.5)		0.2
Cash flow hedges, Net of Tax
Reclassification of losses into net earnings on cash flow hedges	[3]	0.0		(0.3)		0.1
Interest rate
Cash flow hedges, Pretax
Reclassification of losses into net earnings on cash flow hedges	[4]	0.0		0.2		0.1
Cash flow hedges, Net of Tax
Reclassification of losses into net earnings on cash flow hedges	[4]	0.0		0.1		0.0
Unrealized Gains on Available-for-Sale Securities
Components of accumulated other comprehensive income (loss)
Balance at beginning of the period		84.0		207.2
Net current period other comprehensive income (loss)		10.1		(123.2)
Balance at end of the period		94.1		84.0		207.2
Cash flow hedges, Net of Tax
Other comprehensive loss		10.1		(123.2)
Unrealized Loss on Cash Flow Hedges
Components of accumulated other comprehensive income (loss)
Balance at beginning of the period		(0.1)		(0.3)
Net current period other comprehensive income (loss)		0.0		0.2
Balance at end of the period		(0.1)		(0.1)		(0.3)
Cash flow hedges, Net of Tax
Other comprehensive loss		0.0		0.2
Foreign Currency Translation Adjustments
Components of accumulated other comprehensive income (loss)
Balance at beginning of the period		(42.0)		(20.0)
Net current period other comprehensive income (loss)		(35.4)		(22.0)
Balance at end of the period		(77.4)		(42.0)		$ (20.0)
Cash flow hedges, Net of Tax
Other comprehensive loss		$ (35.4)		$ (22.0)

[1] Realized (gains)/losses on available-for-sale securities are recognized in Other income, net.

[2] Reclassification upon liquidation of foreign entities are recognized in Gain on sale of business or Income from discontinued operations, net of tax.

[3] Reclassification to net earnings of derivatives qualifying as effective foreign currency cash flow hedges are recognized in Costs and expenses.

[4] Reclassification to net earnings of derivatives qualifying as effective interest rate cash flow hedges are recognized in Interest expense.