Condensed Consolidating Financial Statements Condensed Cash Flow Statements (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flow provided by operating activities	$ 184.5	$ 178.7	$ 281.1	$ 305.9	$ 340.1
Net cash flow used for investing activities	(41.3)	(41.1)	(43.7)	(48.1)	(50.7)
Proceeds from IPO	615.0	0
Proceeds from long-term debt borrowings	1,598.0	0
Deferred financing fees	(24.8)us-gaap_PaymentsOfFinancingCosts	0us-gaap_PaymentsOfFinancingCosts
Distribution of debt and IPO proceeds to CBS	(2,038.8)us-gaap_PaymentsOfCapitalDistribution	0us-gaap_PaymentsOfCapitalDistribution
Excess tax benefit from stock-based compensation	0	5.5	5.8	2.9	2.3
Net cash contribution from (distribution to) CBS	39.8	(138.6)	(232.6)	(279.7)	(269.4)
Other			(0.2)	(0.2)	(0.2)
Dividends	(88.8)us-gaap_PaymentsOfDividends	0us-gaap_PaymentsOfDividends
Intercompany	0
Net cash flow provided by (used for) financing activities	100.4	(133.1)	(227.0)	(277.0)	(267.3)
Effect of exchange rate changes on cash and cash equivalents	(1.2)	(0.6)	(0.8)	1.8	(3.5)
Net increase in cash and cash equivalents	242.4	3.9	9.6	(17.4)	18.6
Cash and cash equivalents at beginning of period	29.8	20.2	20.2	37.6	19.0
Cash and cash equivalents at end of period	272.2	24.1	29.8	20.2	37.6
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flow provided by operating activities	(0.9)	0	0	0	0
Net cash flow used for investing activities	0	0	0	0	0
Proceeds from IPO	615.0
Proceeds from long-term debt borrowings	0
Deferred financing fees	0
Distribution of debt and IPO proceeds to CBS	(515.0)
Excess tax benefit from stock-based compensation		0	0	0	0
Net cash contribution from (distribution to) CBS	0	0	0	0	0
Other			0	0	0
Dividends	(88.8)
Intercompany	(10.3)
Net cash flow provided by (used for) financing activities	0.9	0	0	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0	0	0	0
Net increase in cash and cash equivalents	0	0	0	0	0
Cash and cash equivalents at beginning of period	0	0	0	0	0
Cash and cash equivalents at end of period	0	0	0	0	0
Subsidiary Issuers
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flow provided by operating activities	(25.6)	0	0	0	0
Net cash flow used for investing activities	0	0	0	0	0
Proceeds from IPO	0
Proceeds from long-term debt borrowings	1,598.0
Deferred financing fees	(24.8)
Distribution of debt and IPO proceeds to CBS	(1,523.8)
Excess tax benefit from stock-based compensation		0	0	0	0
Net cash contribution from (distribution to) CBS	0	0	0	0	0
Other			0	0	0
Dividends	0
Intercompany	206.2
Net cash flow provided by (used for) financing activities	255.6	0	0	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0	0	0	0
Net increase in cash and cash equivalents	230.0	0	0	0	0
Cash and cash equivalents at beginning of period	0	0	0	0	0
Cash and cash equivalents at end of period	230.0	0	0	0	0
Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flow provided by operating activities	213.9	175.0	268.2	277.3	284.3
Net cash flow used for investing activities	(35.3)	(37.2)	(37.0)	(42.5)	(43.4)
Proceeds from IPO	0
Proceeds from long-term debt borrowings	0
Deferred financing fees	0
Distribution of debt and IPO proceeds to CBS	0
Excess tax benefit from stock-based compensation		5.5	5.8	2.9	2.3
Net cash contribution from (distribution to) CBS	39.8	(143.3)	(244.4)	(238.2)	(235.3)
Other			0	0	0
Dividends	0
Intercompany	(197.0)
Net cash flow provided by (used for) financing activities	(157.2)	(137.8)	(238.6)	(235.3)	(233.0)
Effect of exchange rate changes on cash and cash equivalents	0	0	0	0	0
Net increase in cash and cash equivalents	21.4	0	(7.4)	(0.5)	7.9
Cash and cash equivalents at beginning of period	2.1	9.5	9.5	10.0	2.1
Cash and cash equivalents at end of period	23.5	9.5	2.1	9.5	10.0
Non-Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flow provided by operating activities	(2.9)	3.7	12.9	28.6	55.8
Net cash flow used for investing activities	(6.0)	(3.9)	(6.7)	(5.6)	(7.3)
Proceeds from IPO	0
Proceeds from long-term debt borrowings	0
Deferred financing fees	0
Distribution of debt and IPO proceeds to CBS	0
Excess tax benefit from stock-based compensation		0	0	0	0
Net cash contribution from (distribution to) CBS	0	4.7	11.8	(41.5)	(34.1)
Other			(0.2)	(0.2)	(0.2)
Dividends	0
Intercompany	1.1
Net cash flow provided by (used for) financing activities	1.1	4.7	11.6	(41.7)	(34.3)
Effect of exchange rate changes on cash and cash equivalents	(1.2)	(0.6)	(0.8)	1.8	(3.5)
Net increase in cash and cash equivalents	(9.0)	3.9	17.0	(16.9)	10.7
Cash and cash equivalents at beginning of period	27.7	10.7	10.7	27.6	16.9
Cash and cash equivalents at end of period	18.7	14.6	27.7	10.7	27.6
Eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flow provided by operating activities	0	0	0	0	0
Net cash flow used for investing activities	0	0	0	0	0
Proceeds from IPO	0
Proceeds from long-term debt borrowings	0
Deferred financing fees	0
Distribution of debt and IPO proceeds to CBS	0
Excess tax benefit from stock-based compensation		0	0	0	0
Net cash contribution from (distribution to) CBS	0	0	0	0	0
Other			0	0	0
Dividends	0
Intercompany	0
Net cash flow provided by (used for) financing activities	0	0	0	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0	0	0	0
Net increase in cash and cash equivalents	0	0	0	0	0
Cash and cash equivalents at beginning of period	0	0	0	0	0
Cash and cash equivalents at end of period	$ 0	$ 0	$ 0	$ 0	$ 0

The net change during the reporting period in intercompany amounts.

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Net cash contribution (distribution) to parent

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

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Amount of increase (decrease) from the effect of exchange rate changes on cash and cash equivalent balances held in foreign currencies.

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Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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Amount of cash inflow (outflow) of financing activities, excluding discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) of investing activities, excluding discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, excluding discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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Cash outflow to owners or shareholders, excluding ordinary dividends. Includes special dividends.

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The cash outflow for loan and debt issuance costs.

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The cash inflow associated with the amount received from entity's first offering of stock to the public.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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The net cash inflow or outflow from other financing activities. This element is used when there is not a more specific and appropriate element in the taxonomy.

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