Stock-Based Compensation (Summary of Restricted Stock Transactions) (Details)	3 Months Ended
	Mar. 31, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested stock awards outstanding at beginning of period (in shares)	2,142,743
Nonvested stock awards outstanding at end of period (in shares)	2,244,014
Time-vesting shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Awarded (in shares)	108,525
Released (in shares)	(68,923)
Forfeitures (in shares)	(12,000)
Performance-based shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Awarded (in shares)	202,876
Forfeitures (in shares)	(129,207)