Share-Based Compensation - Summary of Restricted Stock and Performance Units Activity (Details) - $ / shares		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock
Restricted Stock and Performance Units [Roll Forward]
Outstanding at January 1		786,079	1,007,794	1,184,299
Granted		173,199	242,835	218,957
Vested	[1]	(213,992)	(443,627)	(389,481)
Forfeitures		(5,554)	(20,923)	(5,981)
Outstanding at December 31		739,732	786,079	1,007,794
Restricted Stock and Performance Units (Weighted Average Grant-date Fair Value) [Abstract]
Weighted Average Grant-Date Fair Value, Outstanding at January 1		$ 63.44	$ 49.47	$ 41.71
Weighted Average Grant-Date Fair Value, Granted		107.57	67.48	65.16
Weighted Average Grant-Date Fair Value, Vested	[1]	51.37	34.11	32.77
Weighted Average Grant-Date Fair Value, Forfeitures		69.03	59.63	66.42
Weighted Average Grant-Date Fair Value, Outstanding at December 31		$ 77.23	$ 63.44	$ 49.47
Performance Units
Restricted Stock and Performance Units [Roll Forward]
Outstanding at January 1		232,088	175,675	127,489
Granted		61,861	77,017	53,102
Vested	[2]	(67,391)	(20,604)	(4,916)
Outstanding at December 31		226,558	232,088	175,675
Restricted Stock and Performance Units (Weighted Average Grant-date Fair Value) [Abstract]
Weighted Average Grant-Date Fair Value, Outstanding at January 1		$ 62.68	$ 59.94	$ 58.25
Weighted Average Grant-Date Fair Value, Granted		108.19	67.57	65.04
Weighted Average Grant-Date Fair Value, Vested	[2]	56.08	57.58	71.19
Weighted Average Grant-Date Fair Value, Outstanding at December 31		$ 77.07	$ 62.68	$ 59.94

[1] The total fair value of awards upon vesting for the years ended December 31, 2017, 2016, and 2015 was $23.3 million, $28.8 million, and $26.3 million, respectively.

[2] The total fair value of awards upon vesting for the years ended December 31, 2017, 2016, and 2015 was $7.5 million, $1.1 million, and $0.3 million, respectively. Upon vesting of the awards in 2016 and 2015, PCA issued 21,111 and 5,090 shares, which included 507 and 174 shares, respectively, for dividends accrued during the vesting period.