Stock-Based Compensation (Details 2) - Nonvested shares	12 Months Ended
	Dec. 31, 2015
Compounded Annual Book Value Per Share Growth 11%
Stock-based compensation
Compounded Annual Book Value Per Share Growth (as a percent)	11.00%
Vesting (as a percent)	10.00%
Compounded Annual Book Value Per Share Growth 12%
Stock-based compensation
Compounded Annual Book Value Per Share Growth (as a percent)	12.00%
Vesting (as a percent)	36.00%
Compounded Annual Book Value Per Share Growth 13%
Stock-based compensation
Compounded Annual Book Value Per Share Growth (as a percent)	13.00%
Vesting (as a percent)	61.00%
Compounded Annual Book Value Per Share Growth 14%
Stock-based compensation
Compounded Annual Book Value Per Share Growth (as a percent)	14.00%
Vesting (as a percent)	87.00%
Maximum | Compounded Annual Book Value Per Share Growth 11%
Stock-based compensation
Compounded Annual Book Value Per Share Growth (as a percent)	11.00%
Vesting (as a percent)	0.00%
Minimum | Compounded Annual Book Value Per Share Growth 15%
Stock-based compensation
Compounded Annual Book Value Per Share Growth (as a percent)	15.00%
Vesting (as a percent)	100.00%