Senior Notes, Secured, and Subordinated Indebtedness - Summary of Senior Notes Redemption Prices Percentage (Details) - Senior Notes	12 Months Ended
	Dec. 31, 2015
8 1/2% Senior Notes due 2020
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	100.00%
April 2016 | 5 3/4% Senior Notes due 2019
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	104.313%
October 2016 | 5 3/4% Senior Notes due 2019
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	102.875%
April 2017 | 5 3/4% Senior Notes due 2019
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	101.438%
April 2018 and Thereafter | 5 3/4% Senior Notes due 2019
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	100.00%
November 2016 | 8 1/2% Senior Notes due 2020
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	104.25%
November 2017 | 8 1/2% Senior Notes due 2020
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	102.125%
November 2018 and Thereafter | 8 1/2% Senior Notes due 2020
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	100.00%
August 2017 | 7% Senior Notes due 2022
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	103.50%
August 2018 | 7% Senior Notes due 2022
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	101.75%
August 2019 and Thereafter | 7% Senior Notes due 2022
Debt Instrument [Line Items]
Percentage of redemption price of principal amount	100.00%