Stockholders' Equity of the Company (Details) (USD $)	9 Months Ended					9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Common Stock [Member]	Dec. 31, 2013 Common Stock [Member]	Sep. 30, 2014 Issuance of Equity - at the market offering [Member] Common Stock [Member]	Sep. 30, 2014 Issuance of Equity under ATM Program [Member]	Sep. 30, 2014 Issuance of Equity under ATM Program [Member] Common Stock [Member]
Common Stock of the Company [Abstract]
Issuance of common stock (Note 7), shares							370,700
Average price per common shares sold							$ 61.01
At the Market Stock Offering Program Aggregate Value Of Common Stock						$ 200,000,000
Net proceeds from issuance of common stock (Note 7)	22,136,000	349,951,000					22,600,000
Common stock, shares issued			83,388,220	82,153,944		2,553,961
At Market Stock Aggregate Gross Sales Price of Common Stock					127,900,000
At the Market Stock Offering Program Remained Available For Issuance							72,100,000
Proceeds from Issuance of Common stock, net							$ 22,300,000