Net Income Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended				1 Months Ended	3 Months Ended		6 Months Ended		1 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 3.375% Convertible Notes [Member]	Jun. 30, 2013 3.375% Convertible Notes [Member]	Jun. 30, 2014 3.375% Convertible Notes [Member]	Jun. 30, 2013 3.375% Convertible Notes [Member]	Jun. 30, 2014 Convertible Debt [Member] 3.375% Convertible Notes [Member]	Dec. 31, 2013 Convertible Debt [Member] 3.375% Convertible Notes [Member]	Feb. 28, 2013 Stock Options [Member]	Jun. 30, 2014 Stock Options [Member]	Jun. 30, 2013 Stock Options [Member]	Jun. 30, 2014 Stock Options [Member]	Jun. 30, 2013 Stock Options [Member]	Feb. 28, 2013 Restricted Stock Units (RSUs) [Member]	Feb. 28, 2013 Performance Share Awards [Member]	Jun. 30, 2014 Performance Share Awards [Member]	Jun. 30, 2013 Equity Award Modification [Member]
Net Income Per Common Share [Line Items]
Weighted average number of diluted shares outstanding adjustment (in shares)	1,187,131	1,071,845	1,254,602	905,620
Adjustments to net income for purposes of computing income available to common stockholders	$ 0	$ 0	$ 0	$ 0
Antidilutive securities excluded from computation of EPS												92,049	139,000	92,049	252,675
Options, granted (in shares)											86,300
Other than options, granted (in shares)																93,989	84,654
Award vesting period																		3 years
Minimum range of target award of stock plan																		0.00%
Maximum range of target award of stock plan																		250.00%
Exercise period of stock options from date of grant														10 years
Exercise period of stock options from date of retirement														5 years
Stock compensation expense			4,108	14,348															10,492
Carrying amount of debt									$ 55,636	$ 55,636
Stated interest rate									3.375%
Potential shares issuable under net share settlement method (in shares)					468,467	99,577	490,460	49,788