Debt Senior Notes (Details) (USD $)			9 Months Ended	0 Months Ended	9 Months Ended									9 Months Ended	0 Months Ended	9 Months Ended	0 Months Ended						0 Months Ended
	Sep. 30, 2013	Sep. 30, 2013 Senior Notes Due 2013 Senior Notes	Sep. 30, 2013 Senior Unsecured Notes Due April 2023	Mar. 19, 2013 Senior Unsecured Notes Due April 2023 Senior Notes	Sep. 30, 2013 Senior Unsecured Notes Due April 2023 Senior Notes	Oct. 03, 2013 Senior Note Due 2017 [Member]	Sep. 30, 2013 Senior Note Due 2017 [Member]	Dec. 31, 2012 Senior Note Due 2017 [Member]	Sep. 30, 2013 7.75% Senior Notes	Sep. 30, 2013 7.75% Senior Notes Senior Notes	Sep. 30, 2013 Senior Notes Due 2021	Dec. 31, 2012 Senior Notes Due 2021	Sep. 30, 2013 Senior Notes Due 2021 Senior Notes	Sep. 30, 2013 Maximum [Member] Senior Unsecured Notes Due April 2023	Mar. 19, 2013 Maximum [Member] Senior Unsecured Notes Due April 2023 Senior Notes	Sep. 30, 2013 Minimum [Member] Senior Unsecured Notes Due April 2023	Mar. 19, 2013 Minimum [Member] Senior Unsecured Notes Due April 2023 Senior Notes	Oct. 03, 2013 Subsequent Event 7.75% Senior Notes Senior Notes	Sep. 19, 2013 Subsequent Event 7.75% Senior Notes Senior Notes	Oct. 03, 2013 Subsequent Event Senior Notes Due January 15, 2022	Nov. 03, 2013 Subsequent Event Senior Notes Due January 15, 2022 Senior Notes	Oct. 03, 2013 Subsequent Event Senior Notes Due January 15, 2022 Senior Notes	Oct. 03, 2013 Subsequent Event Registration Rights Agreement	Oct. 03, 2013 Subsequent Event Registration Rights Agreement Senior Notes	Oct. 03, 2013 Subsequent Event Maximum [Member] Registration Rights Agreement Senior Notes
Debt Instrument [Line Items]
Face amount				$ 300,000,000.0															$ 250,000,000.0			$ 250,000,000.0
Maturity date				Apr. 01, 2023
Interest rate	7.75%	7.75%		5.125%		7.75%	7.75%	7.75%	7.75%	7.75%	6.625%	6.625%	6.625%							5.875%	5.875%
Repurchased amount of aggregate principal																		$ 209,100,000
Coupon rate																				5.875%	5.875%
Yield to maturity																				5.875%	5.875%
File period after closing of offering																							75 days
Declare period after closing of offering																							180 days
Additional Interest																								0.25%	1.00%
Period registration obligations are not satisfied																								90 days
Notice period prior to redemption														0 years 0 months 60 days		0 years 0 months 30 days
Redemption price calculation contributor, percentage				100.00%
Redemption period, percentage of principal amount redeemable															35.00%
Redemption price, percentage				105.125%
Redemption price, percentage of principal remaining after redemption																	65.00%
Redemption period after closing of offering			0 years 0 months 90 days
Redemption period beginning April 1, 2018					12 months