Debt (Senior Convertible Notes) (Narrative) (Details) (USD $)	12 Months Ended					3 Months Ended	12 Months Ended			0 Months Ended	3 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member]	Dec. 31, 2012 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member]	Dec. 31, 2011 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member]	Mar. 31, 2011 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member]	Mar. 31, 2011 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member] Aggregate Principal [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member] Convertible Term 1 [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member] Convertible Term 2 [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member] Convertible Term 3 [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2011 Senior Convertible Notes [Member] Weighted Average [Member]	Mar. 31, 2011 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.25% Notes [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.25% Notes [Member]	Dec. 31, 2009 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.25% Notes [Member]	Nov. 30, 2009 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.25% Notes [Member]	Mar. 31, 2011 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.0% Notes [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.0% Notes [Member]	Dec. 31, 2009 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.0% Notes [Member]	Jun. 30, 2009 Convertible Debt [Member] Unsecured Debt [Member] 2009 4.0% Notes [Member]	Mar. 31, 2011 Convertible Debt [Member] Unsecured Debt [Member] 2011 4.0% Notes [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2011 4.0% Notes [Member]	Mar. 31, 2011 Convertible Debt [Member] Unsecured Debt [Member] 2011 4.25% Notes [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] 2011 4.25% Notes [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] Total Convertible Debt [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] Total Convertible Debt [Member] Scenario, Plan [Member]	Dec. 31, 2013 Convertible Debt [Member] Unsecured Debt [Member] Total Convertible Debt [Member] Scenario, Plan [Member]
Debt Instrument [Line Items]
Debt instrument exchange fee description		During the first quarter of 2011, the Company exchanged $105.3 million of its 4.0% senior convertible notes issued in 2009 (the "2009 4.0% Notes") and $97.0 million of its 4.25% senior convertible notes issued in 2009 (the "2009 4.25% Notes") for identical principal amounts of 2011 4.0% Notes and 2011 4.25% Notes, respectively, for an exchange fee of approximately 50 basis points, or 0.5%, of the aggregate principal amount of the notes exchanged.
Debt instrument, exchanged amount		$ 0	$ 0	$ 202,322,000							$ 97,000,000				$ 105,300,000
Debt instrument, interest rate												4.25%				4.00%				4.00%		4.25%
Debt instrument, exchanged amount, new instrument																			105,300,000		97,000,000
Debt instrument, basis spread, variable interest or fee						0.50%
Debt instrument, terms of conversion feature							if the last reported sale price of the Company’s common stock is greater than or equal to 130% of the applicable conversion price of the 2011 Convertible Notes during at least 20 of the last 30 consecutive trading days ending on and including the last trading day of a calendar quarter, then the applicable 2011 Convertible Notes may be converted during the immediately following calendar quarter (and only during such calendar quarter);	if after any five consecutive trading-day period in which the trading price per $1,000 principal amount of 2011 Convertible Notes for each trading day during such period was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate, then the applicable 2011 Convertible Notes may be converted during the immediately following five business day period;	if the Company effects certain distributions to its shareholders or if the Company is party to a consolidation, merger, binding share exchange, or a sale, transfer, lease or other conveyance of all or substantially all of its assets, pursuant to which the Company’s common stock would be converted into or exchanged for, or would constitute solely the right to receive cash, securities or other assets, or in the case of certain other fundamental changes, then the 2011 Convertible Notes may be converted during the period that is 45 trading days prior to the ex-dividend date or the initial anticipated effective date of the transaction, as applicable.
Debt instrument, effective interest rate		6.73%
Unamortized debt discount and financing costs		4,000,000	9,300,000		17,400,000
Debt instrument, remaining discount amortization period										1 year
Debt instrument, issuance date												Nov. 30, 2009				Jun. 30, 2009
Debt instrument, principal amount		202,300,000												100,000,000				115,000,000		105,300,000		97,000,000	215,000,000
Debt instrument, maturity date												Dec. 15, 2014				Jun. 15, 2014				Jun. 15, 2014		Dec. 15, 2014
Debt instrument, payment terms												The 2009 4.25% Notes bear interest at a rate of 4.25% per year, payable semi-annually in arrears, on June 15 and December 15 of each year.				The 2009 4.0% Notes bear interest at a rate of 4.0% per year, payable semi-annually in arrears, on June 15 and December 15 of each year.
Debt instrument, convertible, latest date												Dec. 12, 2014				Jun. 13, 2014
Debt instrument, convertible, conversion ratio												64.6162				63.4417
Debt instrument, conversion price per share												$ 15.48				$ 15.76				$ 15.76		$ 15.48
Debt issuance cost	9,600,000												3,700,000				5,400,000
Convertible notes, guarantees		The 4.25% and 4.0% senior convertible notes are guaranteed by certain of the Company's 100%-owned direct and indirect domestic operating subsidiaries
Debt instrument, restrictive covenants		There are no financial covenants associated with these notes; however, there are certain nonfinancial provisions and covenants.
Short-term debt, intent to refinance																									The Company expects to refinance the $215.0 million principal amount of the senior convertible notes on a long-term basis either through its 2013 Credit Facility or through other sources of available funding and, therefore, has included the carrying amounts of these notes as a component of long-term debt as of December 31, 2013.
Short-term debt, refinanced, amount																								$ 215,000,000