Derivative Financial Instruments (Summary Of Interest Rate Swaps) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
2.303% Interest Rate Swap [Member]
Derivative [Line Items]
Trade Date	Mar. 31, 2011
Notional amount	$ 100.0
Interest Rate Paid	2.303%
Coveage Period	March 2011 to November 2015
Risk Coverage	Term Loan A
2.523% Interest Rate Swap [Member]
Derivative [Line Items]
Trade Date	Mar. 31, 2011
Notional amount	200.0
Interest Rate Paid	2.523%
Coveage Period	March 2011 to November 2015
Risk Coverage	Term Loan B
1.928% Interest Rate Swap [Member]
Derivative [Line Items]
Trade Date	Mar. 27, 2012
Notional amount	250.0
Interest Rate Paid	1.928%
Coveage Period	March 2012 to March 2018
Risk Coverage	Term Loan B
2.810% Interest Rate Swap [Member]
Derivative [Line Items]
Trade Date	Mar. 27, 2012
Notional amount	200.0
Interest Rate Paid	2.81%
Coveage Period	November 2015 to March 2018
Risk Coverage	Term Loan B
1.398% Interest Rate Swap [Member]
Derivative [Line Items]
Trade Date	Apr. 16, 2013
Notional amount	$ 250.0
Interest Rate Paid	1.398%
Coveage Period	November 2015 to March 2018
Risk Coverage	Term Loan A