Stockholders' Equity- Shares of Common Stock Issued During 2014 under Employee Stock Purchase Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares Available, Beginning Balance	213,760			61,247
Shares Authorized for Issuance	250,000		250,000
Shares Issued during Period (Shares)	22,723	36,305	38,459
Shares Available, Ending Balance	213,760			61,247
Shares Issued during Period (per Share Price)	$ 34.37	$ 21.49	$ 20.39