Debt and Other Long-Term Liabilities (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended				3 Months Ended		9 Months Ended								3 Months Ended					3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Quantity	Sep. 30, 2013	Dec. 31, 2013	Mar. 12, 2013 Senior Notes Original Notes [Member]	Jun. 09, 2014 Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Senior Notes Senior Unsecured Notes due 2021	Jun. 30, 2014 Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Credit Facility Federal Funds Effective Swap Rate [Member]	Sep. 30, 2014 Credit Facility London Interbank Offered Rate (LIBOR) [Member]	Sep. 30, 2014 Convertible Notes	Dec. 31, 2013 Convertible Notes	Sep. 30, 2009 Convertible Notes	Sep. 30, 2014 Period, June 15, 2017 To June 14, 2018 [Member] Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Period, June 9, 2014 To June 14, 2017 [Member] Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Period, June 15, 2018 To June 14, 2019 [Member] Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Period, June 15, 2019 To June 14, 2020 [Member] Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Period, June 15, 2020 To June 15, 2021 [Member] Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Revolving Line of Credit Credit Facility	Dec. 31, 2013 Revolving Line of Credit Credit Facility	Sep. 30, 2014 Term Loans	Sep. 30, 2014 Term Loans Credit Facility	Dec. 31, 2013 Term Loans Credit Facility	Sep. 30, 2014 Common Stock [Member]	Sep. 30, 2014 Common Stock [Member]	Sep. 30, 2014 Scenario One [Member] Period, June 9, 2014 To June 14, 2017 [Member] Senior Notes Senior Unsecured Notes due 2021	Sep. 30, 2014 Scenario Two [Member] Period, June 9, 2014 To June 14, 2017 [Member] Senior Notes Senior Unsecured Notes due 2021
Debt Instrument [Line Items]
Principal amount of debt						$ 350,000,000	$ 300,000,000.0
Interest rate, per year						6.00%	5.875%					4.00%		4.00%
Cash interest expense	11,517,000	7,304,000	29,646,000	17,716,000
Proceeds from issuance of debt	0	0	295,500,000	343,769,000		343,800,000	294,000,000
Redemption rate															104.406%		102.938%	101.469%	100.00%								100.00%	105.875%
Maximum aggregate principal amount of notes redeemable																35.00%
Minimum aggregate principal amount of Notes outstanding after redemption																65.00%
Percentage of principal amount of notes required to be offered to purchase the Notes upon a change in control								101.00%
Percentage of principal amount of notes required to be offered to purchase the Notes if certain asset sales are made								100.00%
Minimum percentage of aggregate principal amount of Notes required to declare the principal amount plus accrued and unpaid interest on the Notes to be immediately due and payable in event of default								25.00%
Additional interest payable, per annum, following a registration default, percentage								0.25%
Maximum additional interest payable, per annum, following a registration default, percentage								1.00%
Loss on extinguishment of debt	55,000	1,000	2,018,000	5,950,000								300,000								1,700,000
Line of credit facility, maximum borrowing capacity																				600,000,000.0			150,000,000.0
Sublimit for issuance of letters of credit																				75,000,000.0
Sublimit for swingline loans																				50,000,000.0
Sublimit for loans in certain foreign countries																				75,000,000.0
Line of credit facility, option to increase borrowing capacity																				200,000,000.0
Basis spread on variable interest rate										0.50%	1.00%
Stated interest rate, minimum										0.25%	1.25%
Stated interest rate, maximum										1.00%	2.00%
Interest rate on amounts outstanding under the credit facility																						2.02%
Debt outstanding	1,008,125,000		1,008,125,000		745,523,000			300,000,000	300,000,000				51,148,000							210,000,000	0		148,125,000	344,375,000
Number of notes retired			51,148
Conversion of debt, cash	$ 33,425,000	$ 30,000	$ 51,149,000	$ 169,664,000								$ 51,100,000
Conversion of debt, issuance of common stock (shares)																									248,944	431,760