Summary of Significant Accounting Policies (Details) (USD $)	1 Months Ended	6 Months Ended	1 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Mar. 31, 2014 Current repurchase program	Jun. 30, 2013 Current repurchase program	Jun. 30, 2014 Current repurchase program	Jun. 30, 2014 Current repurchase program	Jun. 30, 2014 Prior repurchase program	Jun. 30, 2013 Prior repurchase program	Jun. 30, 2013 Prior repurchase program	Jun. 30, 2014 Common Stock [Member]
Accounting Policies Disclosure [Line Items]
Stock split conversion ratio	2
Adjustments to Additional Paid in Capital, Stock Split		$ 0								$ 78,000,000
Summary of Significant Accounting Policies (Textual) [Abstract]
Authorized amount from board of directors for share repurchase			250,000,000				200,000,000
Share repurchase program expiry date			Dec. 31, 2015
Shares repurchased under the program					63,600	340,146		2,588,496	2,588,496
Cost of shares repurchased		12,500,000			2,500,000	12,500,000		49,900,000	49,900,000
Shares repurchased settled in subsequent month				$ 9,700,000