Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

The following table provides a summary of the Company's outstanding long-term debt and the fair values based on quoted market prices in less active markets as of December 31, 2015 and December 31, 2014:

						Level 2 Fair Value as of
	Principal Amount at Par		Issuance Date	Maturity	Interest Due Dates	December 31, 2015		December 31, 2014
	(in millions)					(in millions)
5.50% Senior Notes	$	700.0	February 2015	2022	April 15 and October 15	$	717.5	$	—
5.875% Senior Notes	800.0		February 2015	2025	April 15 and October 15	820.0		—
5.750% Senior Notes	400.0		February 2014	2024	March 1 and September 1	411.0		416.0
5.375% Senior Notes	500.0		February 2013	2021	February 1 and August 1	525.0		520.0