Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of the components of basic and diluted shares in the EPS Calculation [Abstract]
Weighted-average basic common shares outstanding	176,100,000	175,800,000	175,400,000
Potential number of shares issuable under the Company's LTSIP	200,000	300,000	600,000
Weighted-average diluted common shares outstanding	176,300,000	176,100,000	176,000,000
Dividend Reinvestment and Stock Purchase Plan [Abstract]
Shares issued	0	0	0
Shares reserved for future issuance	19,872,261