Income Taxes (Income Tax Reconciliation and Unrecognized Tax Benefits) (Details) - USD ($)		3 Months Ended		9 Months Ended
	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income before income taxes and equity in net income (loss) of unconsolidated entities		$ 50,800,000	$ 46,300,000	$ 139,200,000	$ 136,500,000
Equity in net income (loss) of unconsolidated entities		0	400,000	(1,000,000)	700,000
Total		50,800,000	46,700,000	138,200,000	137,200,000
Income tax expense		$ 16,900,000	$ 16,500,000	$ 40,200,000	$ 46,500,000
Effective income tax rate		33.30%	35.30%	29.10%	33.90%
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Current liabilities		$ 8,800,000		$ 8,800,000		$ 8,900,000
Non-current liabilities		5,700,000		5,700,000		5,400,000
Total liability for unrecognized tax benefits		$ 14,500,000		$ 14,500,000		$ 14,300,000
Concentration Risk [Line Items]
Respective decrease in taxes (as a percent)		2.00%		4.80%
Gain on sale of business		$ 0	$ 0	$ 17,500,000	$ 0
Geographic Concentration Risk | Cash, Cash Equivalents and Investments | Non-U.S. [Member]
Concentration Risk [Line Items]
Percentage of cash, cash equivalents and investments held by operations outside of US				73.00%
Disposal Group, Disposed of by Sale, Not Discontinued Operations | HelloWallet
Concentration Risk [Line Items]
Gain on sale of business	$ 17,500,000.0