Share-Based Payments - Summary of Grants, Exchanges and Forfeitures of Restricted Stock and RSUs (Details) - LTIP [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Grant Date Fair Value	$ 19,148	$ 17,496	$ 16,477
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning balance (in shares)	105,561	150,110	107,385
Grant (in shares)	28,070	27,700	92,056
Vested (in shares)	(67,934)	(72,249)	(49,331)
Forfeitures (in shares)	0	0	0
Outstanding, ending balance (in shares)	65,697	105,561	150,110
RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning balance (in shares)	1,632,746	1,703,775	1,242,810
Grant (in shares)	1,006,800	912,916	903,068
Vested (in shares)	(739,388)	(938,541)	(397,030)
Forfeitures (in shares)	(47,201)	(45,404)	(45,073)
Outstanding, ending balance (in shares)	1,852,957	1,632,746	1,703,775