Stockholders' Equity (Schedule of Deferred and Restricted Stock Units Transactions) (Details) - Deferred and Restricted Stock Unit - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Balance at beginning of the period (in shares)	264,406	449,055	506,447
Issued (in shares)	6,073	5,354	68,340
Granted (in shares)	252,068	101,650	95,079
Dividend equivalents (in shares)	10,243	8,036	9,799
Forfeited (in shares)	(9,079)	(9,557)	(3,094)
Vested (in shares)	(177,563)	(290,132)	(227,516)
Balance at end of the period (in shares)	346,148	264,406	449,055
Weighted Average Price
Outstanding exercise price (in usd per share)	$ 83.84	$ 72.55	$ 50.00
Issued (in usd per share)	89.82	106.10	108.61
Granted (in usd per share)	81.07	103.20	109.50
Dividend equivalent (in usd per share)	89.65	89.66	104.12
Forfeited (in usd per share)	89.67	76.71	72.96
Exercised (in usd per share)	69.65	74.83	40.39
Outstanding exercise price (in usd per share)	$ 87.54	$ 83.84	$ 72.55